Protocol

Heads up! This article is about the protocol for a stable release of Minecraft Java Edition (1.21, protocol 767). For the Java Edition pre-releases, see Pre-release protocol. For the incomplete Bedrock Edition docs, see Bedrock Protocol. For the old Pocket Edition, see Pocket Edition Protocol Documentation.

This page presents a dissection of the current Minecraft protocol.

If you're having trouble, check out the FAQ or ask for help in the IRC channel #mcdevs on irc.libera.chat (More Information).

Note: While you may use the contents of this page without restriction to create servers, clients, bots, etc; substantial reproductions of this page must be attributed IAW CC BY-SA 4.0.

The changes between versions may be viewed at Protocol History.

Definitions

The Minecraft server accepts connections from TCP clients and communicates with them using messages. A message is a sequence of bytes sent over the TCP connection. The meaning of a message depends both on its message ID and the current state of the connection. The initial state of each connection is Handshaking, and state is switched using the messages Handshake and Login Success.

Data types

All data sent over the network (except for VarInt and VarLong) is big-endian, that is the bytes are sent from most significant byte to least significant byte. The majority of everyday computers are little-endian, therefore it may be necessary to change the endianness before sending data over the network.

Name	Size (bytes)	Encodes	Notes
Boolean	1	Either false or true	True is encoded as 0x01, false as 0x00.
Byte	1	An integer between -128 and 127	Signed 8-bit integer, two's complement
Unsigned Byte	1	An integer between 0 and 255	Unsigned 8-bit integer
Short	2	An integer between -32768 and 32767	Signed 16-bit integer, two's complement
Unsigned Short	2	An integer between 0 and 65535	Unsigned 16-bit integer
Int	4	An integer between -2147483648 and 2147483647	Signed 32-bit integer, two's complement
Long	8	An integer between -9223372036854775808 and 9223372036854775807	Signed 64-bit integer, two's complement
Float	4	A single-precision 32-bit IEEE 754 floating point number
Double	8	A double-precision 64-bit IEEE 754 floating point number
String (n)	≥ 1 ≤ (n×3) + 3	A sequence of Unicode scalar values	UTF-8 string prefixed with its size in bytes as a VarInt. Maximum length of n characters, which varies by context. The encoding used on the wire is regular UTF-8, not Java's "slight modification". However, the length of the string for purposes of the length limit is its number of UTF-16 code units, that is, scalar values > U+FFFF are counted as two. Up to n × 3 bytes can be used to encode a UTF-8 string comprising n code units when converted to UTF-16, and both of those limits are checked. Maximum n value is 32767. The + 3 is due to the max size of a valid length VarInt.
Text Component	Varies	See Text formatting#Text components	Encoded as a NBT Tag, with the type of tag used depending on the case: As a String Tag: For components only containing text (no styling, no events etc.). As a Compound Tag: Every other case.
JSON Text Component	≥ 1 ≤ (262144×3) + 3	See Text formatting#Text components	The maximum permitted length when decoding is 262144, but the Notchian server since 1.20.3 refuses to encode longer than 32767. This may be a bug.
Identifier	≥ 1 ≤ (32767×3) + 3	See Identifier below	Encoded as a String with max length of 32767.
VarInt	≥ 1 ≤ 5	An integer between -2147483648 and 2147483647	Variable-length data encoding a two's complement signed 32-bit integer; more info in their section
VarLong	≥ 1 ≤ 10	An integer between -9223372036854775808 and 9223372036854775807	Variable-length data encoding a two's complement signed 64-bit integer; more info in their section
Entity Metadata	Varies	Miscellaneous information about an entity	See Entity_metadata#Entity Metadata Format
Slot	Varies	An item stack in an inventory or container	See Slot Data
NBT	Varies	Depends on context	See NBT
Position	8	An integer/block position: x (-33554432 to 33554431), z (-33554432 to 33554431), y (-2048 to 2047)	x as a 26-bit integer, followed by z as a 26-bit integer, followed by y as a 12-bit integer (all signed, two's complement). See also the section below.
Angle	1	A rotation angle in steps of 1/256 of a full turn	Whether or not this is signed does not matter, since the resulting angles are the same.
UUID	16	A UUID	Encoded as an unsigned 128-bit integer (or two unsigned 64-bit integers: the most significant 64 bits and then the least significant 64 bits)
BitSet	Varies	See #BitSet below	A length-prefixed bit set.
Fixed BitSet (n)	ceil(n / 8)	See #Fixed BitSet below	A bit set with a fixed length of n bits.
Optional X	0 or size of X	A field of type X, or nothing	Whether or not the field is present must be known from the context.
Array of X	count times size of X	Zero or more fields of type X	The count must be known from the context.
X Enum	size of X	A specific value from a given list	The list of possible values and how each is encoded as an X must be known from the context. An invalid value sent by either side will usually result in the client being disconnected with an error or even crashing.
Byte Array	Varies	Depends on context	This is just a sequence of zero or more bytes, its meaning should be explained somewhere else, e.g. in the packet description. The length must also be known from the context.
ID or X	size of VarInt + (size of X or 0)	See #ID or X below	Either a registry ID or an inline data definition of type X.
ID Set	Varies	See #ID Set below	Set of registry IDs specified either inline or as a reference to a tag.
Sound Event	Varies	See #Sound Event below	Parameters for a sound event.

Identifier

Identifiers are a namespaced location, in the form of minecraft:thing. If the namespace is not provided, it defaults to minecraft (i.e. thing is minecraft:thing). Custom content should always be in its own namespace, not the default one. Both the namespace and value can use all lowercase alphanumeric characters (a-z and 0-9), dot (.), dash (-), and underscore (_). In addition, values can use slash (/). The naming convention is lower_case_with_underscores. More information. For ease of determining whether a namespace or value is valid, here are regular expressions for each:

• Namespace: [a-z0-9.-_]
• Value: [a-z0-9.-_/]

VarInt and VarLong

Variable-length format such that smaller numbers use fewer bytes. These are very similar to Protocol Buffer Varints: the 7 least significant bits are used to encode the value and the most significant bit indicates whether there's another byte after it for the next part of the number. The least significant group is written first, followed by each of the more significant groups; thus, VarInts are effectively little endian (however, groups are 7 bits, not 8).

VarInts are never longer than 5 bytes, and VarLongs are never longer than 10 bytes. Within these limits, unnecessarily long encodings (e.g. 81 00 to encode 1) are allowed.

Pseudocode to read and write VarInts and VarLongs:

private static final int SEGMENT_BITS = 0x7F;
private static final int CONTINUE_BIT = 0x80;

public int readVarInt() {
    int value = 0;
    int position = 0;
    byte currentByte;

    while (true) {
        currentByte = readByte();
        value |= (currentByte & SEGMENT_BITS) << position;

        if ((currentByte & CONTINUE_BIT) == 0) break;

        position += 7;

        if (position >= 32) throw new RuntimeException("VarInt is too big");
    }

    return value;
}

public long readVarLong() {
    long value = 0;
    int position = 0;
    byte currentByte;

    while (true) {
        currentByte = readByte();
        value |= (long) (currentByte & SEGMENT_BITS) << position;

        if ((currentByte & CONTINUE_BIT) == 0) break;

        position += 7;

        if (position >= 64) throw new RuntimeException("VarLong is too big");
    }

    return value;
}

public void writeVarInt(int value) {
    while (true) {
        if ((value & ~SEGMENT_BITS) == 0) {
            writeByte(value);
            return;
        }

        writeByte((value & SEGMENT_BITS) | CONTINUE_BIT);

        // Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
        value >>>= 7;
    }
}

public void writeVarLong(long value) {
    while (true) {
        if ((value & ~((long) SEGMENT_BITS)) == 0) {
            writeByte(value);
            return;
        }

        writeByte((value & SEGMENT_BITS) | CONTINUE_BIT);

        // Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
        value >>>= 7;
    }
}

Note Minecraft's VarInts are identical to LEB128 with the slight change of throwing a exception if it goes over a set amount of bytes.

Note that Minecraft's VarInts are not encoded using Protocol Buffers; it's just similar. If you try to use Protocol Buffers Varints with Minecraft's VarInts, you'll get incorrect results in some cases. The major differences:

• Minecraft's VarInts are all signed, but do not use the ZigZag encoding. Protocol buffers have 3 types of Varints: uint32 (normal encoding, unsigned), sint32 (ZigZag encoding, signed), and int32 (normal encoding, signed). Minecraft's are the int32 variety. Because Minecraft uses the normal encoding instead of ZigZag encoding, negative values always use the maximum number of bytes.
• Minecraft's VarInts are never longer than 5 bytes and its VarLongs will never be longer than 10 bytes, while Protocol Buffer Varints will always use 10 bytes when encoding negative numbers, even if it's an int32.

Sample VarInts:

Value	Hex bytes	Decimal bytes
0	0x00	0
1	0x01	1
2	0x02	2
127	0x7f	127
128	0x80 0x01	128 1
255	0xff 0x01	255 1
25565	0xdd 0xc7 0x01	221 199 1
2097151	0xff 0xff 0x7f	255 255 127
2147483647	0xff 0xff 0xff 0xff 0x07	255 255 255 255 7
-1	0xff 0xff 0xff 0xff 0x0f	255 255 255 255 15
-2147483648	0x80 0x80 0x80 0x80 0x08	128 128 128 128 8

Sample VarLongs:

Value	Hex bytes	Decimal bytes
0	0x00	0
1	0x01	1
2	0x02	2
127	0x7f	127
128	0x80 0x01	128 1
255	0xff 0x01	255 1
2147483647	0xff 0xff 0xff 0xff 0x07	255 255 255 255 7
9223372036854775807	0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0x7f	255 255 255 255 255 255 255 255 127
-1	0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0x01	255 255 255 255 255 255 255 255 255 1
-2147483648	0x80 0x80 0x80 0x80 0xf8 0xff 0xff 0xff 0xff 0x01	128 128 128 128 248 255 255 255 255 1
-9223372036854775808	0x80 0x80 0x80 0x80 0x80 0x80 0x80 0x80 0x80 0x01	128 128 128 128 128 128 128 128 128 1

Position

Note: What you are seeing here is the latest version of the Data types article, but the position type was different before 1.14.

64-bit value split into three signed integer parts:

• x: 26 MSBs
• z: 26 middle bits
• y: 12 LSBs

For example, a 64-bit position can be broken down as follows:

Example value (big endian): 01000110000001110110001100 10110000010101101101001000 001100111111

• The red value is the X coordinate, which is 18357644 in this example.
  
• The blue value is the Z coordinate, which is -20882616 in this example.
  
• The green value is the Y coordinate, which is 831 in this example.
  

Encoded as follows:

((x & 0x3FFFFFF) << 38) | ((z & 0x3FFFFFF) << 12) | (y & 0xFFF)

And decoded as:

val = read_long();
x = val >> 38;
y = val << 52 >> 52;
z = val << 26 >> 38;

Note: The above assumes that the right shift operator sign extends the value (this is called an arithmetic shift), so that the signedness of the coordinates is preserved. In many languages, this requires the integer type of val to be signed. In the absence of such an operator, the following may be useful:

if x >= 1 << 25 { x -= 1 << 26 }
if y >= 1 << 11 { y -= 1 << 12 }
if z >= 1 << 25 { z -= 1 << 26 }

Fixed-point numbers

Some fields may be stored as fixed-point numbers, where a certain number of bits represent the signed integer part (number to the left of the decimal point) and the rest represent the fractional part (to the right). Floating point numbers (float and double), in contrast, keep the number itself (mantissa) in one chunk, while the location of the decimal point (exponent) is stored beside it. Essentially, while fixed-point numbers have lower range than floating point numbers, their fractional precision is greater for higher values.

Prior to version 1.9 a fixed-point format with 5 fraction bits and 27 integer bits was used to send entity positions to the client. Some uses of fixed point remain in modern versions, but they differ from that format.

Most programming languages lack support for fractional integers directly, but you can represent them as integers. The following C or Java-like pseudocode converts a double to a fixed-point integer with n fraction bits:

 x_fixed = (int)(x_double * (1 << n));

And back again:

 x_double = (double)x_fixed / (1 << n);

Bit sets

The types BitSet and Fixed BitSet represent packed lists of bits. The Notchian implementation uses Java's BitSet class.

BitSet

Bit sets of type BitSet are prefixed by their length in longs.

Field Name	Field Type	Meaning
Length	VarInt	Number of longs in the following array. May be 0 (if no bits are set).
Data	Array of Long	A packed representation of the bit set as created by BitSet.toLongArray.

The ith bit is set when (Data[i / 64] & (1 << (i % 64))) != 0, where i starts at 0.

Fixed BitSet

Bit sets of type Fixed BitSet (n) have a fixed length of n bits, encoded as ceil(n / 8) bytes. Note that this is different from BitSet, which uses longs.

Field Name	Field Type	Meaning
Data	Byte Array (n)	A packed representation of the bit set as created by BitSet.toByteArray, padded with zeroes at the end to fit the specified length.

The ith bit is set when (Data[i / 8] & (1 << (i % 8))) != 0, where i starts at 0. This encoding is not equivalent to the long array in BitSet.

Registry references

ID or X

Represents a data record of type X, either inline, or by reference to a registry implied by context.

Field Name	Field Type	Meaning
ID	VarInt	0 if value of type X is given inline; otherwise registry ID + 1.
Value	Optional X	Only present if ID is 0.

ID Set

Represents a set of IDs in a certain registry (implied by context), either directly (enumerated IDs) or indirectly (tag name).

Field Name	Field Type	Meaning
Type	VarInt	Value used to determine the data that follows. It can be either: 0 - Represents a named set of IDs defined by a tag. Anything else - Represents an ad-hoc set of IDs enumerated inline.
Tag Name	Optional Identifier	The registry tag defining the ID set. Only present if Type is 0.
IDs	Optional Array of VarInt	An array of registry IDs. Only present if Type is not 0. The size of the array is equal to Type - 1.

Registry data

These types are commonly used in conjuction with ID or X to specify custom data inline.

Sound Event

Describes a sound that can be played.

Name	Type	Description
Sound Name	Identifier
Has Fixed Range	Boolean	Whether this sound has a fixed range, as opposed to a variable volume based on distance.
Fixed Range	Optional Float	The maximum range of the sound. Only present if Has Fixed Range is true.

Other definitions

Term	Definition
Player	When used in the singular, Player always refers to the client connected to the server.
Entity	Entity refers to any item, player, mob, minecart or boat etc. See the Minecraft Wiki article for a full list.
EID	An EID — or Entity ID — is a 4-byte sequence used to identify a specific entity. An entity's EID is unique on the entire server.
XYZ	In this document, the axis names are the same as those shown in the debug screen (F3). Y points upwards, X points east, and Z points south.
Meter	The meter is Minecraft's base unit of length, equal to the length of a vertex of a solid block. The term “block” may be used to mean “meter” or “cubic meter”.
Registry	A table describing static, gameplay-related objects of some kind, such as the types of entities, block states or biomes. The entries of a registry are typically associated with textual or numeric identifiers, or both. Minecraft has a unified registry system used to implement most of the registries, including blocks, items, entities, biomes and dimensions. These "ordinary" registries associate entries with both namespaced textual identifiers (see #Identifier), and signed (positive) 32-bit numeric identifiers. There is also a registry of registries listing all of the registries in the registry system. Some other registries, most notably the block state registry, are however implemented in a more ad-hoc fashion. Some registries, such as biomes and dimensions, can be customized at runtime by the server (see Registry Data), while others, such as blocks, items and entities, are hardcoded. The contents of the hardcoded registries can be extracted via the built-in Data Generators system.
Block state	Each block in Minecraft has 0 or more properties, which in turn may have any number of possible values. These represent, for example, the orientations of blocks, poweredness states of redstone components, and so on. Each of the possible permutations of property values for a block is a distinct block state. The block state registry assigns a numeric identifier to every block state of every block. A current list of properties and state ID ranges is found on burger. Alternatively, the vanilla server now includes an option to export the current block state ID mapping, by running java -DbundlerMainClass=net.minecraft.data.Main -jar minecraft_server.jar --reports. See Data Generators for more information.
Notchian	The official implementation of vanilla Minecraft as developed and released by Mojang.
Sequence	The action number counter for local block changes, incremented by one when clicking a block with a hand, right clicking an item, or starting or finishing digging a block. Counter handles latency to avoid applying outdated block changes to the local world. Also is used to revert ghost blocks created when placing blocks, using buckets, or breaking blocks.

Message format

Messages cannot be larger than 2²¹ − 1 or 2097151 bytes (the maximum that can be sent in a 3-byte VarInt). Moreover, the length field must not be longer than 3 bytes, even if the encoded value is within the limit. Unnecessarily long encodings at 3 bytes or below are still allowed. For compressed messages, this applies to the Message Length field, i.e. the compressed length.

Without compression

Field Name	Field Type	Notes
Length	VarInt	Length of Message ID + Data
Message ID	VarInt
Data	Byte Array	Depends on the connection state and message ID, see the sections below

With compression

Once a Set Compression message (with a non-negative threshold) is sent, zlib compression is enabled for all following messages. The format of a message changes slightly to include the size of the uncompressed message.

Present?	Compressed?	Field Name	Field Type	Notes
always	No	Message Length	VarInt	Length of (Data Length) + length of compressed (Message ID + Data)
if size >= threshold	No	Data Length	VarInt	Length of uncompressed (Message ID + Data)
	Yes	Message ID	VarInt	zlib compressed message ID (see the sections below)
		Data	Byte Array	zlib compressed message data (see the sections below)
if size < threshold	No	Data Length	VarInt	0 to indicate uncompressed
		Message ID	VarInt	message ID (see the sections below)
		Data	Byte Array	message data (see the sections below)

For serverbound messages, the uncompressed length of (Message ID + Data) must not be greater than 2²³ or 8388608 bytes. Not that a length equal to 2²³ is permitted, which differs from the compressed length limit. The Notchian client, on the other hand, has no limit for the uncompressed length of incoming compressed messages.

If the size of the buffer containing the message data and ID (as a VarInt) is smaller than the threshold specified in the message Set Compression. It will be sent as uncompressed. This is done by setting the data length as 0. (Comparable to sending a non-compressed format with an extra 0 between the length, and message data).

If it's larger than or equal to the threshold, then it follows the regular compressed protocol format.

The Notchian server (but not client) rejects compressed messages smaller than the threshold. Uncompressed messages exceeding the threshold, however, are accepted.

Compression can be disabled by sending the message Set Compression with a negative Threshold, or not sending the Set Compression message at all.

Handshaking

Clientbound

There are no clientbound messages in the Handshaking state, since the protocol immediately switches to a different state after the client sends the first message.

Serverbound

Handshake

This causes the server to switch into the target state.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Handshaking	Server	Protocol Version	VarInt	See protocol version numbers (currently 767 in Minecraft 1.21).
			Server Address	String (255)	Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information. Note that SRV records are a simple redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide example.org as server address in addition to connecting to it.
			Server Port	Unsigned Short	Default is 25565. The Notchian server does not use this information.
			Next State	VarInt Enum	1 for Status, 2 for Login, 3 for Transfer.

Legacy Server List Ping

This message uses a nonstandard format. It is never length-prefixed, and the message ID is an Unsigned Byte instead of a VarInt.

While not technically part of the current protocol, legacy clients may send this message to initiate Server List Ping, and modern servers should handle it correctly. The format of this message is a remnant of the pre-Netty age, before the switch to Netty in 1.7 brought the standard format that is recognized now. This message merely exists to inform legacy clients that they can't join our modern server.

Message ID	State	Bound To	Field Name	Field Type	Notes
0xFE	Handshaking	Server	Payload	Unsigned Byte	always 1 (0x01).

See Server List Ping#1.6 for the details of the protocol that follows this message.

Status

Main article: Server List Ping

Clientbound

Status Response

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Status	Client
			JSON Response	String (32767)	See Server List Ping#Status Response; as with all strings this is prefixed by its length as a VarInt.

Ping Response (status)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Status	Client	Payload	Long	Should be the same as sent by the client.

Serverbound

Status Request

The status can only be requested once immediately after the handshake, before any ping. The server won't respond otherwise.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Status	Server	no fields

Ping Request (status)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Status	Server	Payload	Long	May be any number. Notchian clients use a system-dependent time value which is counted in milliseconds.

Login

The login process is as follows:

1. C→S: Handshake with Next State set to 2 (login)
2. C→S: Login Start
3. S→C: Encryption Request
4. Client auth (if enabled)
5. C→S: Encryption Response
6. Server auth (if enabled)
7. Both enable encryption
8. S→C: Set Compression (optional)
9. S→C: Login Success
10. C→S: Login Acknowledged

Set Compression, if present, must be sent before Login Success. Note that anything sent after Set Compression must use the Post Compression message format.

Three modes of operation are possible depending on how the messages are sent:

• Online-mode with encryption
• Offline-mode with encryption
• Offline-mode without encryption

For online-mode servers (the ones with authentication enabled), encryption is always mandatory, and the entire process described above needs to be followed.

For offline-mode servers (the ones with authentication disabled), encryption is optional, and part of the process can be skipped. In that case Login Start is directly followed by Login Success. The Notchian server only uses UUID v3 for offline player UUIDs, deriving it from the string OfflinePlayer:<player's name> For example, Notch’s offline UUID would be chosen from the string OfflinePlayer:Notch. This is not a requirement however, the UUID can be set to anything.

As of 1.21, the Notchian server never uses encryption in offline mode.

See Protocol Encryption for details.

Clientbound

Disconnect (login)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Login	Client	Reason	JSON Text Component	The reason why the player was disconnected.

Encryption Request

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Login	Client	Server ID	String (20)	Appears to be empty.
			Public Key Length	VarInt	Length of Public Key.
			Public Key	Byte Array	The server's public key, in bytes.
			Verify Token Length	VarInt	Length of Verify Token. Always 4 for Notchian servers.
			Verify Token	Byte Array	A sequence of random bytes generated by the server.
			Should authenticate	Boolean	Wheather the client should attempt to authenticate through mojang servers.

See Protocol Encryption for details.

Login Success

Message ID	State	Bound To	Field Name		Field Type		Notes
0x02	Login	Client	UUID		UUID
			Username		String (16)
			Number Of Properties		VarInt		Number of elements in the following array.
			Property	Name	Array	String (32767)
				Value		String (32767)
				Is Signed		Boolean
				Signature		Optional String (32767)	Only if Is Signed is true.
			Strict Error Handling		Boolean		Whether the client should immediately disconnect upon a message processing error. The Notchian client silently ignores them when this flag is false. This field was temporarily added in 1.20.5 as a way to aid modded servers with the transition to the new data pack & registry system, allowing them to tell the client to silently ignore messages containing inconsistent data. It will likely be removed soon.

The Property field looks like response of Mojang API#UUID to Profile and Skin/Cape, except using the protocol format instead of JSON. That is, each player will usually have one property with Name being “textures” and Value being a base64-encoded JSON string, as documented at Mojang API#UUID to Profile and Skin/Cape. An empty properties array is also acceptable, and will cause clients to display the player with one of the two default skins depending their UUID (again, see the Mojang API page).

Set Compression

Enables compression. If compression is enabled, all following messages are encoded in the compressed message format. Negative values will disable compression, meaning the message format should remain in the uncompressed message format. However, this message is entirely optional, and if not sent, compression will also not be enabled (the notchian server does not send the message when compression is disabled).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x03	Login	Client	Threshold	VarInt	Maximum size of a message before it is compressed.

Login Plugin Request

Used to implement a custom handshaking flow together with Login Plugin Response.

Unlike plugin messages in "play" mode, these messages follow a lock-step request/response scheme, where the client is expected to respond to a request indicating whether it understood. The notchian client always responds that it hasn't understood, and sends an empty payload.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x04	Login	Client	Message ID	VarInt	Generated by the server - should be unique to the connection.
			Channel	Identifier	Name of the plugin channel used to send the data.
			Data	Byte Array (1048576)	Any data, depending on the channel. The length of this array must be inferred from the message length.

In Notchian client, the maximum data length is 1048576 bytes.

Cookie Request (login)

Requests a cookie that was previously stored.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x05	Login	Client	Key		Identifier		The identifier of the cookie.

Serverbound

Login Start

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Login	Server	Name	String (16)	Player's Username.
			Player UUID	UUID	The UUID of the player logging in. Unused by the Notchian server.

Encryption Response

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Login	Server	Shared Secret Length	VarInt	Length of Shared Secret.
			Shared Secret	Byte Array	Shared Secret value, encrypted with the server's public key.
			Verify Token Length	VarInt	Length of Verify Token.
			Verify Token	Byte Array	Verify Token value, encrypted with the same public key as the shared secret.

See Protocol Encryption for details.

Login Plugin Response

Message ID	State	Bound To	Field Name	Field Type	Notes
0x02	Login	Server	Message ID	VarInt	Should match ID from server.
			Successful	Boolean	true if the client understood the request, false otherwise. When false, no payload follows.
			Data	Optional Byte Array (1048576)	Any data, depending on the channel. The length of this array must be inferred from the message length.

In Notchian server, the maximum data length is 1048576 bytes.

Login Acknowledged

Acknowledgement to the Login Success message sent by the server.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x03	Login	Server	no fields

This message switches the connection state to configuration.

Cookie Response (login)

Response to a Cookie Request (login) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x04	Login	Server	Key		Identifier		The identifier of the cookie.
			Has Payload		Boolean		The payload is only present if the cookie exists on the client.
			Payload Length		Optional VarInt		Length of the following byte array.
			Payload		Optional Byte Array (5120)		The data of the cookie, if any.

Configuration

Clientbound

Cookie Request (configuration)

Requests a cookie that was previously stored.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x00	Configuration	Client	Key		Identifier		The identifier of the cookie.

Clientbound Plugin Message (configuration)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses several plugin channels. These internal channels are in the minecraft namespace.

More information on how it works on Dinnerbone's blog. More documentation about internal and popular registered channels are here.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Configuration	Client	Channel	Identifier	Name of the plugin channel used to send the data.
			Data	Byte Array (1048576)	Any data. The length of this array must be inferred from the message length.

In Notchian client, the maximum data length is 1048576 bytes.

Disconnect (configuration)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x02	Configuration	Client	Reason	Text Component	The reason why the player was disconnected.

Finish Configuration

Sent by the server to notify the client that the configuration process has finished. The client answers with Acknowledge Finish Configuration whenever it is ready to continue.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x03	Configuration	Client	no fields

This message switches the connection state to play.

Clientbound Keep Alive (configuration)

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same payload (see Serverbound Keep Alive). If the client does not respond to a Keep Alive message within 15 seconds after it was sent, the server kicks the client. Vice versa, if the server does not send any keep-alives for 20 seconds, the client will disconnect and yields a "Timed out" exception.

The Notchian server uses a system-dependent time in milliseconds to generate the keep alive ID value.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x04	Configuration	Client	Keep Alive ID	Long

Ping (configuration)

Message is not used by the Notchian server. When sent to the client, client responds with a Pong message with the same id.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x05	Configuration	Client	ID	Int

Reset Chat

Message ID	State	Bound To	Field Name	Field Type	Notes
0x06	Configuration	Client	no fields

Registry Data

Represents certain registries that are sent from the server and are applied on the client.

See Registry Data for details.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x07	Configuration	Client
			Registry ID		Identifier
			Entry Count		VarInt		Number of entries in the following array.
			Entries	Entry ID	Array	Identifier
				Has Data		Boolean	Whether the entry has any data following.
				Data		NBT	Entry data. Only present if Has Data is true.

Remove Resource Pack (configuration)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x08	Configuration	Client	Has UUID	Boolean	Whether a specific resource pack should be removed, or all of them.
			UUID	Optional UUID	The UUID of the resource pack to be removed. Only present if the previous field is true.

Add Resource Pack (configuration)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x09	Configuration	Client	UUID	UUID	The unique identifier of the resource pack.
			URL	String (32767)	The URL to the resource pack.
			Hash	String (40)	A 40 character hexadecimal, case-insensitive SHA-1 hash of the resource pack file. If it's not a 40 character hexadecimal string, the client will not use it for hash verification and likely waste bandwidth.
			Forced	Boolean	The Notchian client will be forced to use the resource pack from the server. If they decline they will be kicked from the server.
			Has Prompt Message	Boolean	Whether a custom message should be used on the resource pack prompt.
			Prompt Message	Optional Text Component	This is shown in the prompt making the client accept or decline the resource pack. Only present if the previous field is true.

Store Cookie (configuration)

Stores some arbitrary data on the client, which persists between server transfers. The Notchian client only accepts cookies of up to 5 kiB in size.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0A	Configuration	Client	Key		Identifier		The identifier of the cookie.
			Payload		Byte Array (5120)		The data of the cookie.

Transfer (configuration)

Notifies the client that it should transfer to the given server. Cookies previously stored are preserved between server transfers.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0B	Configuration	Client	Host		String		The hostname or IP of the server.
			Port		VarInt		The port of the server.

Feature Flags

Used to enable and disable features, generally experimental ones, on the client.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0C	Configuration	Client	Total Features	VarInt	Number of features that appear in the array below.
			Feature Flags	Array of Identifier

As of 1.21, the following feature flags are available:

• minecraft:vanilla - enables vanilla features
• minecraft:bundle - enables support for the bundle
• minecraft:trade_rebalance - enables support for the rebalanced villager trades

Update Tags (configuration)

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0D	Configuration	Client	Length of the array		VarInt
			Array of tags	Registry	Array	Identifier	Registry identifier (Vanilla expects tags for the registries minecraft:block, minecraft:item, minecraft:fluid, minecraft:entity_type, and minecraft:game_event)
				Array of Tag		(See below)

Tag arrays look like:

Field Name		Field Type		Notes
Length		VarInt		Number of elements in the following array
Tags	Tag name	Array	Identifier
	Count		VarInt	Number of elements in the following array
	Entries		Array of VarInt	Numeric IDs of the given type (block, item, etc.). This list replaces the previous list of IDs for the given tag. If some preexisting tags are left unmentioned, a warning is printed.

See Tag on the Minecraft Wiki for more information, including a list of vanilla tags.

Clientbound Known Packs

Informs the client of which data packs are present on the server. The client is expected to respond with its own Serverbound Known Packs message. The Notchian server does not continue with Configuration until it receives a response.

The Notchian client requires the minecraft:core pack with version 1.21 for a normal login sequence. This message must be sent before the Registry Data messages.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0E	Configuration	Client	Known Pack Count		VarInt		The number of known packs in the following array.
			Known Packs	Namespace	Array	String
				ID		String
				Version		String

Custom Report Details (configuration)

Contains a list of key-value text entries that are included in any crash or disconnection report generated during connection to the server.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0F	Configuration	Client	Details Count		VarInt (32)		The number of details in the following array.
			Details	Title	Array	String (128)
				Description		String (4096)

Server Links (configuration)

This message contains a list of links that the Notchian client will display in the menu available from the pause menu. Link labels can be built-in or custom (i.e., any text).

Message ID	State	Bound To	Field Name		Field Type		Notes
0x10	Configuration	Client	Links Count		VarInt		The number of links in the following array.
			Links	Is built-in	Array	Boolean	Determines if the following label is built-in (from enum) or custom (text component).
				Label		VarInt Enum / Text Component	See below.
				URL		String	Valid URL.

ID	Name	Notes
0	Bug Report	Displayed on connection error screen; included as a comment in the disconnection report.
1	Community Guidelines
2	Support
3	Status
4	Feedback
5	Community
6	Website
7	Forums
8	News
9	Announcements

Serverbound

Client Information (configuration)

Sent when the player connects, or when settings are changed.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Configuration	Server	Locale	String (16)	e.g. en_GB.
			View Distance	Byte	Client-side render distance, in chunks.
			Chat Mode	VarInt Enum	0: enabled, 1: commands only, 2: hidden. See Chat#Client chat mode for more information.
			Chat Colors	Boolean	“Colors” multiplayer setting. Can the chat be colored?
			Displayed Skin Parts	Unsigned Byte	Bit mask, see below.
			Main Hand	VarInt Enum	0: Left, 1: Right.
			Enable text filtering	Boolean	Enables filtering of text on signs and written book titles. Currently always false (i.e. the filtering is disabled)
			Allow server listings	Boolean	Servers usually list online players, this option should let you not show up in that list.

Displayed Skin Parts flags:

• Bit 0 (0x01): Cape enabled
• Bit 1 (0x02): Jacket enabled
• Bit 2 (0x04): Left Sleeve enabled
• Bit 3 (0x08): Right Sleeve enabled
• Bit 4 (0x10): Left Pants Leg enabled
• Bit 5 (0x20): Right Pants Leg enabled
• Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Cookie Response (configuration)

Response to a Cookie Request (configuration) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x01	Configuration	Server	Key		Identifier		The identifier of the cookie.
			Has Payload		Boolean		The payload is only present if the cookie exists on the client.
			Payload Length		Optional VarInt		Length of the following byte array.
			Payload		Optional Byte Array (5120)		The data of the cookie, if any.

Serverbound Plugin Message (configuration)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses some plugin channels. These internal channels are in the minecraft namespace.

More documentation on this: https://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Note that the length of Data is known only from the message length, since the message has no length field of any kind.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x02	Configuration	Server	Channel	Identifier	Name of the plugin channel used to send the data.
			Data	Byte Array (32767)	Any data, depending on the channel. minecraft: channels are documented here. The length of this array must be inferred from the message length.

In Notchian server, the maximum data length is 32767 bytes.

Acknowledge Finish Configuration

Sent by the client to notify the server that the configuration process has finished. It is sent in response to the server's Finish Configuration.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x03	Configuration	Server	no fields

This message switches the connection state to play.

Serverbound Keep Alive (configuration)

The server will frequently send out a keep-alive (see Clientbound Keep Alive), each containing a random ID. The client must respond with the same message.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x04	Configuration	Server	Keep Alive ID	Long

Pong (configuration)

Response to the clientbound message (Ping) with the same id.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x05	Configuration	Server	ID	Int	id is the same as the ping message

Resource Pack Response (configuration)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x06	Configuration	Server
			UUID	UUID	The unique identifier of the resource pack received in the Add Resource Pack (configuration) request.
			Result	VarInt Enum	Result ID (see below).

Result can be one of the following values:

ID	Result
0	Successfully downloaded
1	Declined
2	Failed to download
3	Accepted
4	Downloaded
5	Invalid URL
6	Failed to reload
7	Discarded

Serverbound Known Packs

Informs the server of which data packs are present on the client. The client sends this in response to Clientbound Known Packs.

If the client specifies a pack in this message, the server should omit its contained data from the Registry Data message.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x07	Configuration	Server	Known Pack Count		VarInt		The number of known packs in the following array.
			Known Packs	Namespace	Array	String
				ID		String
				Version		String

Play

Clientbound

Bundle Delimiter

The delimiter for a bundle of messages. When received, the client should store every subsequent message it receives, and wait until another delimiter is received. Once that happens, the client is guaranteed to process every message in the bundle on the same tick, and the client should stop storing messages.

As of 1.20.6, the Notchian server only uses this to ensure Spawn Entity and associated messages used to configure the entity happen on the same tick. Each entity gets a separate bundle.

The Notchian client doesn't allow more than 4096 messages in the same bundle.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Play	Client	no fields

Spawn Entity

Sent by the server when an entity (aside from Experince Orb) is created.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Play	Client	Entity ID	VarInt	A unique integer ID mostly used in the protocol to identify the entity.
			Entity UUID	UUID	A unique identifier that is mostly used in persistence and places where the uniqueness matters more.
			Type	VarInt	ID in the minecraft:entity_type registry (see "type" field in Entity metadata#Entities).
			X	Double
			Y	Double
			Z	Double
			Pitch	Angle	To get the real pitch, you must divide this by (256.0F / 360.0F)
			Yaw	Angle	To get the real yaw, you must divide this by (256.0F / 360.0F)
			Head Yaw	Angle	Only used by living entities, where the head of the entity may differ from the general body rotation.
			Data	VarInt	Meaning dependent on the value of the Type field, see Object Data for details.
			Velocity X	Short	Same units as Set Entity Velocity.
			Velocity Y	Short
			Velocity Z	Short

The points listed below should be considered when this message is used to spawn a player entity.

When in online mode, the UUIDs must be valid and have valid skin blobs. In offline mode, the Notchian server uses UUID v3 and chooses the player's UUID by using the String OfflinePlayer:<player name>, encoding it in UTF-8 (and case-sensitive), then processes it with UUID.nameUUIDFromBytes.

For NPCs UUID v2 should be used. Note:

<+Grum> i will never confirm this as a feature you know that :)

In an example UUID, xxxxxxxx-xxxx-Yxxx-xxxx-xxxxxxxxxxxx, the UUID version is specified by Y. So, for UUID v3, Y will always be 3, and for UUID v2, Y will always be 2.

Spawn Experience Orb

Spawns one or more experience orbs.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x02	Play	Client	Entity ID	VarInt
			X	Double
			Y	Double
			Z	Double
			Count	Short	The amount of experience this orb will reward once collected.

Entity Animation

Sent whenever an entity should change animation.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x03	Play	Client	Entity ID	VarInt	Player ID.
			Animation	Unsigned Byte	Animation ID (see below).

Animation can be one of the following values:

ID	Animation
0	Swing main arm
2	Leave bed
3	Swing offhand
4	Critical effect
5	Magic critical effect

Award Statistics

Sent as a response to Client Status (id 1). Will only send the changed values if previously requested.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x04	Play	Client	Count		VarInt		Number of elements in the following array.
			Statistic	Category ID	Array	VarInt	See below.
				Statistic ID		VarInt	See below.
				Value		VarInt	The amount to set it to.

Categories (these are namespaced, but with : replaced with .):

Name	ID	Registry
minecraft.mined	0	Blocks
minecraft.crafted	1	Items
minecraft.used	2	Items
minecraft.broken	3	Items
minecraft.picked_up	4	Items
minecraft.dropped	5	Items
minecraft.killed	6	Entities
minecraft.killed_by	7	Entities
minecraft.custom	8	Custom

Blocks, Items, and Entities use block (not block state), item, and entity ids.

Custom has the following (unit only matters for clients):

Name	ID	Unit
minecraft.leave_game	0	None
minecraft.play_one_minute	1	Time
minecraft.time_since_death	2	Time
minecraft.time_since_rest	3	Time
minecraft.sneak_time	4	Time
minecraft.walk_one_cm	5	Distance
minecraft.crouch_one_cm	6	Distance
minecraft.sprint_one_cm	7	Distance
minecraft.walk_on_water_one_cm	8	Distance
minecraft.fall_one_cm	9	Distance
minecraft.climb_one_cm	10	Distance
minecraft.fly_one_cm	11	Distance
minecraft.walk_under_water_one_cm	12	Distance
minecraft.minecart_one_cm	13	Distance
minecraft.boat_one_cm	14	Distance
minecraft.pig_one_cm	15	Distance
minecraft.horse_one_cm	16	Distance
minecraft.aviate_one_cm	17	Distance
minecraft.swim_one_cm	18	Distance
minecraft.strider_one_cm	19	Distance
minecraft.jump	20	None
minecraft.drop	21	None
minecraft.damage_dealt	22	Damage
minecraft.damage_dealt_absorbed	23	Damage
minecraft.damage_dealt_resisted	24	Damage
minecraft.damage_taken	25	Damage
minecraft.damage_blocked_by_shield	26	Damage
minecraft.damage_absorbed	27	Damage
minecraft.damage_resisted	28	Damage
minecraft.deaths	29	None
minecraft.mob_kills	30	None
minecraft.animals_bred	31	None
minecraft.player_kills	32	None
minecraft.fish_caught	33	None
minecraft.talked_to_villager	34	None
minecraft.traded_with_villager	35	None
minecraft.eat_cake_slice	36	None
minecraft.fill_cauldron	37	None
minecraft.use_cauldron	38	None
minecraft.clean_armor	39	None
minecraft.clean_banner	40	None
minecraft.clean_shulker_box	41	None
minecraft.interact_with_brewingstand	42	None
minecraft.interact_with_beacon	43	None
minecraft.inspect_dropper	44	None
minecraft.inspect_hopper	45	None
minecraft.inspect_dispenser	46	None
minecraft.play_noteblock	47	None
minecraft.tune_noteblock	48	None
minecraft.pot_flower	49	None
minecraft.trigger_trapped_chest	50	None
minecraft.open_enderchest	51	None
minecraft.enchant_item	52	None
minecraft.play_record	53	None
minecraft.interact_with_furnace	54	None
minecraft.interact_with_crafting_table	55	None
minecraft.open_chest	56	None
minecraft.sleep_in_bed	57	None
minecraft.open_shulker_box	58	None
minecraft.open_barrel	59	None
minecraft.interact_with_blast_furnace	60	None
minecraft.interact_with_smoker	61	None
minecraft.interact_with_lectern	62	None
minecraft.interact_with_campfire	63	None
minecraft.interact_with_cartography_table	64	None
minecraft.interact_with_loom	65	None
minecraft.interact_with_stonecutter	66	None
minecraft.bell_ring	67	None
minecraft.raid_trigger	68	None
minecraft.raid_win	69	None
minecraft.interact_with_anvil	70	None
minecraft.interact_with_grindstone	71	None
minecraft.target_hit	72	None
minecraft.interact_with_smithing_table	73	None

Units:

• None: just a normal number (formatted with 0 decimal places)
• Damage: value is 10 times the normal amount
• Distance: a distance in centimeters (hundredths of blocks)
• Time: a time span in ticks

Acknowledge Block Change

Acknowledges a user-initiated block change. After receiving this message, the client will display the block state sent by the server instead of the one predicted by the client.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x05	Play	Client	Sequence ID	VarInt	Represents the sequence to acknowledge, this is used for properly syncing block changes to the client after interactions.

Set Block Destroy Stage

0–9 are the displayable destroy stages and each other number means that there is no animation on this coordinate.

Block break animations can still be applied on air; the animation will remain visible although there is no block being broken. However, if this is applied to a transparent block, odd graphical effects may happen, including water losing its transparency. (An effect similar to this can be seen in normal gameplay when breaking ice blocks)

If you need to display several break animations at the same time you have to give each of them a unique Entity ID. The entity ID does not need to correspond to an actual entity on the client. It is valid to use a randomly generated number.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x06	Play	Client	Entity ID	VarInt	The ID of the entity breaking the block.
			Location	Position	Block Position.
			Destroy Stage	Byte	0–9 to set it, any other value to remove it.

Block Entity Data

Sets the block entity associated with the block at the given location.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x07	Play	Client	Location	Position
			Type	VarInt	The type of the block entity
			NBT Data	NBT	Data to set. May be a TAG_END (0), in which case the block entity at the given location is removed (though this is not required since the client will remove the block entity automatically on chunk unload or block removal).

Block Action

This message is used for a number of actions and animations performed by blocks, usually non-persistent. The client ignores the provided block type and instead uses the block state in their world.

See Block Actions for a list of values.

This message uses a block ID from the minecraft:block registry, not a block state.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x08	Play	Client	Location	Position	Block coordinates.
			Action ID (Byte 1)	Unsigned Byte	Varies depending on block — see Block Actions.
			Action Parameter (Byte 2)	Unsigned Byte	Varies depending on block — see Block Actions.
			Block Type	VarInt	The block type ID for the block. This value is unused by the Notchian client, as it will infer the type of block based on the given position.

Block Update

Fired whenever a block is changed within the render distance.

Changing a block in a chunk that is not loaded is not a stable action. The Notchian client currently uses a shared empty chunk which is modified for all block changes in unloaded chunks; while in 1.9 this chunk never renders in older versions the changed block will appear in all copies of the empty chunk. Servers should avoid sending block changes in unloaded chunks and clients should ignore such messages.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x09	Play	Client	Location	Position	Block Coordinates.
			Block ID	VarInt	The new block state ID for the block as given in the block state registry.

Boss Bar

Message ID	State	Bound To	Field Name		Field Type	Notes
0x0A	Play	Client	UUID		UUID	Unique ID for this bar.
			Action		VarInt Enum	Determines the layout of the remaining message.
			Action	Field Name
			0: add	Title	Text Component
				Health	Float	From 0 to 1. Values greater than 1 do not crash a Notchian client, and start rendering part of a second health bar at around 1.5.
				Color	VarInt Enum	Color ID (see below).
				Division	VarInt Enum	Type of division (see below).
				Flags	Unsigned Byte	Bit mask. 0x1: should darken sky, 0x2: is dragon bar (used to play end music), 0x04: create fog (previously was also controlled by 0x02).
			1: remove	no fields	no fields	Removes this boss bar.
			2: update health	Health	Float	as above
			3: update title	Title	Text Component
			4: update style	Color	VarInt Enum	Color ID (see below).
				Dividers	VarInt Enum	as above
			5: update flags	Flags	Unsigned Byte	as above

ID	Color
0	Pink
1	Blue
2	Red
3	Green
4	Yellow
5	Purple
6	White

ID	Type of division
0	No division
1	6 notches
2	10 notches
3	12 notches
4	20 notches

Change Difficulty

Changes the difficulty setting in the client's option menu

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0B	Play	Client	Difficulty	Unsigned Byte	0: peaceful, 1: easy, 2: normal, 3: hard.
			Difficulty locked?	Boolean

Chunk Batch Finished

Marks the end of a chunk batch. The Notchian client marks the time it receives this message and calculates the elapsed duration since the beginning of the chunk batch. The server uses this duration and the batch size received in this message to estimate the number of milliseconds elapsed per chunk received. This value is then used to calculate the desired number of chunks per tick through the formula 25 / millisPerChunk, which is reported to the server through Chunk Batch Received. This likely uses 25 instead of the normal tick duration of 50 so chunk processing will only use half of the client's and network's bandwidth.

The Notchian client uses the samples from the latest 15 batches to estimate the milliseconds per chunk number.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0C	Play	Client	Batch size	VarInt	Number of chunks.

Chunk Batch Start

Marks the start of a chunk batch. The Notchian client marks and stores the time it receives this message.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0D	Play	Client	no fields

Chunk Biomes

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0E	Play	Client
			Number of chunks		VarInt		Number of elements in the following array
			Chunk biome data	Chunk Z	Array	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
				Chunk X		Int	Chunk coordinate (block coordinate divided by 16, rounded down)
				Size		VarInt	Size of Data in bytes
				Data		Byte Array	Chunk data structure, with sections containing only the Biomes field

Note: The order of X and Z is inverted, because the client reads them as one big-endian Long, with Z being the upper 32 bits.

Clear Titles

Clear the client's current title information, with the option to also reset it.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0F	Play	Client	Reset	Boolean

Command Suggestions Response

The server responds with a list of auto-completions of the last word sent to it. In the case of regular chat, this is a player username. Command names and parameters are also supported. The client sorts these alphabetically before listing them.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x10	Play	Client
			ID		VarInt		Transaction ID.
			Start		VarInt		Start of the text to replace.
			Length		VarInt		Length of the text to replace.
			Count		VarInt		Number of elements in the following array.
			Matches	Match	Array	String (32767)	One eligible value to insert, note that each command is sent separately instead of in a single string, hence the need for Count. Note that for instance this doesn't include a leading / on commands.
				Has tooltip		Boolean	True if the following is present.
				Tooltip		Optional Text Component	Tooltip to display; only present if previous boolean is true.

Commands

Lists all of the commands on the server, and how they are parsed.

This is a directed graph, with one root node. Each redirect or child node must refer only to nodes that have already been declared.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x11	Play	Client	Count	VarInt	Number of elements in the following array.
			Nodes	Array of Node	An array of nodes.
			Root index	VarInt	Index of the root node in the previous array.

For more information on this message, see the Command Data article.

Close Container

This message is sent from the server to the client when a window is forcibly closed, such as when a chest is destroyed while it's open. The notchian client disregards the provided window ID and closes any active window.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x12	Play	Client	Window ID	Unsigned Byte	This is the ID of the window that was closed. 0 for inventory.

Set Container Content

The inventory slots

Replaces the contents of a container window. Sent by the server upon initialization of a container window or the player's inventory, and in response to state ID mismatches (see #Click Container).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x13	Play	Client	Window ID	Unsigned Byte	The ID of window which items are being sent for. 0 for player inventory. The client ignores any messages targeting a Window ID other than the current one. However, an exception is made for the player inventory, which may be targeted at any time. (The Notchian server does not appear to utilize this special case.)
			State ID	VarInt	A server-managed sequence number used to avoid desynchronization; see #Click Container.
			Count	VarInt	Number of elements in the following array.
			Slot Data	Array of Slot
			Carried Item	Slot	Item being dragged with the mouse.

See inventory windows for further information about how slots are indexed. Use Open Screen to open the container on the client.

Set Container Property

This message is used to inform the client that part of a GUI window should be updated.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x14	Play	Client	Window ID	Unsigned Byte
			Property	Short	The property to be updated, see below.
			Value	Short	The new value for the property, see below.

The meaning of the Property field depends on the type of the window. The following table shows the known combinations of window type and property, and how the value is to be interpreted.

Window type	Property	Value
Furnace	0: Fire icon (fuel left)	counting from fuel burn time down to 0 (in-game ticks)
	1: Maximum fuel burn time	fuel burn time or 0 (in-game ticks)
	2: Progress arrow	counting from 0 to maximum progress (in-game ticks)
	3: Maximum progress	always 200 on the notchian server
Enchantment Table	0: Level requirement for top enchantment slot	The enchantment's xp level requirement
	1: Level requirement for middle enchantment slot
	2: Level requirement for bottom enchantment slot
	3: The enchantment seed	Used for drawing the enchantment names (in SGA) clientside. The same seed is used to calculate enchantments, but some of the data isn't sent to the client to prevent easily guessing the entire list (the seed value here is the regular seed bitwise and 0xFFFFFFF0).
	4: Enchantment ID shown on mouse hover over top enchantment slot	The enchantment id (set to -1 to hide it), see below for values
	5: Enchantment ID shown on mouse hover over middle enchantment slot
	6: Enchantment ID shown on mouse hover over bottom enchantment slot
	7: Enchantment level shown on mouse hover over the top slot	The enchantment level (1 = I, 2 = II, 6 = VI, etc.), or -1 if no enchant
	8: Enchantment level shown on mouse hover over the middle slot
	9: Enchantment level shown on mouse hover over the bottom slot
Beacon	0: Power level	0-4, controls what effect buttons are enabled
	1: First potion effect	Potion effect ID for the first effect, or -1 if no effect
	2: Second potion effect	Potion effect ID for the second effect, or -1 if no effect
Anvil	0: Repair cost	The repair's cost in xp levels
Brewing Stand	0: Brew time	0 – 400, with 400 making the arrow empty, and 0 making the arrow full
	1: Fuel time	0 - 20, with 0 making the arrow empty, and 20 making the arrow full
Stonecutter	0: Selected recipe	The index of the selected recipe. -1 means none is selected.
Loom	0: Selected pattern	The index of the selected pattern. 0 means none is selected, 0 is also the internal id of the "base" pattern.
Lectern	0: Page number	The current page number, starting from 0.

For an enchanting table, the following numerical IDs are used:

Numerical ID	Enchantment ID	Enchantment Name
0	minecraft:protection	Protection
1	minecraft:fire_protection	Fire Protection
2	minecraft:feather_falling	Feather Falling
3	minecraft:blast_protection	Blast Protection
4	minecraft:projectile_protection	Projectile Protection
5	minecraft:respiration	Respiration
6	minecraft:aqua_affinity	Aqua Affinity
7	minecraft:thorns	Thorns
8	minecraft:depth_strider	Depth Strider
9	minecraft:frost_walker	Frost Walker
10	minecraft:binding_curse	Curse of Binding
11	minecraft:soul_speed	Soul Speed
12	minecraft:swift_sneak	Swift Sneak
13	minecraft:sharpness	Sharpness
14	minecraft:smite	Smite
15	minecraft:bane_of_arthropods	Bane of Arthropods
16	minecraft:knockback	Knockback
17	minecraft:fire_aspect	Fire Aspect
18	minecraft:looting	Looting
19	minecraft:sweeping_edge	Sweeping Edge
20	minecraft:efficiency	Efficiency
21	minecraft:silk_touch	Silk Touch
22	minecraft:unbreaking	Unbreaking
23	minecraft:fortune	Fortune
24	minecraft:power	Power
25	minecraft:punch	Punch
26	minecraft:flame	Flame
27	minecraft:infinity	Infinity
28	minecraft:luck_of_the_sea	Luck of the Sea
29	minecraft:lure	Lure
30	minecraft:loyalty	Loyalty
31	minecraft:impaling	Impaling
32	minecraft:riptide	Riptide
33	minecraft:channeling	Channeling
34	minecraft:multishot	Multishot
35	minecraft:quick_charge	Quick Charge
36	minecraft:piercing	Piercing
37	minecraft:density	Density
38	minecraft:breach	Breach
39	minecraft:wind_burst	Wind Burst
40	minecraft:mending	Mending
41	minecraft:vanishing_curse	Curse of Vanishing

Set Container Slot

Sent by the server when an item in a slot (in a window) is added/removed.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x15	Play	Client	Window ID	Byte	The window which is being updated. 0 for player inventory. The client ignores any messages targeting a Window ID other than the current one; see below for exceptions.
			State ID	VarInt	A server-managed sequence number used to avoid desynchronization; see #Click Container.
			Slot	Short	The slot that should be updated.
			Slot Data	Slot

If Window ID is 0, the hotbar and offhand slots (slots 36 through 45) may be updated even when a different container window is open. (The Notchian server does not appear to utilize this special case.) Updates are also restricted to those slots when the player is looking at a creative inventory tab other than the survival inventory. (The Notchian server does not handle this restriction in any way, leading to MC-242392.)

If Window ID is -1, the item being dragged with the mouse is set. In this case, State ID and Slot are ignored.

If Window ID is -2, any slot in the player's inventory can be updated irrespective of the current container window. In this case, State ID is ignored, and the Notchian server uses a bogus value of 0. Used by the Notchian server to implement the #Pick Item functionality.

When a container window is open, the server never sends updates targeting Window ID 0—all of the window types include slots for the player inventory. The client must automatically apply changes targeting the inventory portion of a container window to the main inventory; the server does not resend them for ID 0 when the window is closed. However, since the armor and offhand slots are only present on ID 0, updates to those slots occurring while a window is open must be deferred by the server until the window's closure.

Cookie Request (play)

Requests a cookie that was previously stored.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x16	Play	Client	Key		Identifier		The identifier of the cookie.

Set Cooldown

Applies a cooldown period to all items with the given type. Used by the Notchian server with enderpearls. This message should be sent when the cooldown starts and also when the cooldown ends (to compensate for lag), although the client will end the cooldown automatically. Can be applied to any item, note that interactions still get sent to the server with the item but the client does not play the animation nor attempt to predict results (i.e block placing).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x17	Play	Client	Item ID	VarInt	Numeric ID of the item to apply a cooldown to.
			Cooldown Ticks	VarInt	Number of ticks to apply a cooldown for, or 0 to clear the cooldown.

Chat Suggestions

Unused by the Notchian server. Likely provided for custom servers to send chat message completions to clients.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x18	Play	Client	Action	VarInt Enum	0: Add, 1: Remove, 2: Set
			Count	VarInt	Number of elements in the following array.
			Entries	Array of String (32767)

Clientbound Plugin Message (play)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses several plugin channels. These internal channels are in the minecraft namespace.

More information on how it works on Dinnerbone's blog. More documentation about internal and popular registered channels are here.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x19	Play	Client	Channel	Identifier	Name of the plugin channel used to send the data.
			Data	Byte Array (1048576)	Any data. The length of this array must be inferred from the message length.

In Notchian client, the maximum data length is 1048576 bytes.

Damage Event

Message ID	State	Bound To	Field Name		Field Type		Notes
0x1A	Play	Client
			Entity ID		VarInt		The ID of the entity taking damage
			Source Type ID		VarInt		The type of damage in the minecraft:damage_type registry, defined by the Registry Data message.
			Source Cause ID		VarInt		The ID + 1 of the entity responsible for the damage, if present. If not present, the value is 0
			Source Direct ID		VarInt		The ID + 1 of the entity that directly dealt the damage, if present. If not present, the value is 0. If this field is present: and damage was dealt indirectly, such as by the use of a projectile, this field will contain the ID of such projectile; and damage was dealt dirctly, such as by manually attacking, this field will contain the same value as Source Cause ID.
			Has Source Position		Boolean		Indicates the presence of the three following fields. The Notchian server sends the Source Position when the damage was dealt by the /damage command and a position was specified
			Source Position X		Optional Double		Only present if Has Source Position is true
			Source Position Y		Optional Double		Only present if Has Source Position is true
			Source Position Z		Optional Double		Only present if Has Source Position is true

Debug Sample

Sample data that is sent periodically after the client has subscribed with Debug Sample Subscription.

The Notchian server only sends debug samples to players that are server operators.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1B	Play	Client	Sample Length	VarInt	The length of the following array.
			Sample	Long Array	Array of type-dependent samples.
			Sample Type	VarInt Enum	See below.

Types:

Id	Name	Description
0	Tick time	Four different tick-related metrics, each one represented by one long on the array. They are measured in nano-seconds, and are as follows: Full tick time: Aggregate of the three times below; Server tick time: Main server tick logic; Tasks time: Tasks scheduled to execute after the main logic; Idle time: Time idling to complete the full 50ms tick cycle.

Delete Message

Removes a message from the client's chat. This only works for messages with signatures, system messages cannot be deleted with this message.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1C	Play	Client	Message ID	VarInt	The message Id + 1, used for validating message signature. The next field is present only when value of this field is equal to 0.
			Signature	Optional Byte Array (256)	The previous message's signature. Always 256 bytes and not length-prefixed.

Disconnect (play)

Sent by the server before it disconnects a client. The client assumes that the server has already closed the connection by the time the message arrives.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1D	Play	Client	Reason	Text Component	Displayed to the client when the connection terminates.

Disguised Chat Message

Main article: Chat

Sends the client a chat message, but without any message signing information.

The Notchian server uses this message when the console is communicating with players through commands, such as /say, /tell, /me, among others.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1E	Play	Client	Message	Text Component	This is used as the content parameter when formatting the message on the client.
			Chat Type	VarInt	The type of chat in the minecraft:chat_type registry, defined by the Registry Data message.
			Sender Name	Text Component	The name of the one sending the message, usually the sender's display name. This is used as the sender parameter when formatting the message on the client.
			Has Target Name	Boolean	True if target name is present.
			Target Name	Text Component	The name of the one receiving the message, usually the receiver's display name. Only present if previous boolean is true. This is used as the target parameter when formatting the message on the client.

Entity Event

Entity statuses generally trigger an animation for an entity. The available statuses vary by the entity's type (and are available to subclasses of that type as well).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1F	Play	Client	Entity ID	Int
			Entity Status	Byte Enum	See Entity statuses for a list of which statuses are valid for each type of entity.

Explosion

Sent when an explosion occurs (creepers, TNT, and ghast fireballs).

Each block in Records is set to air. Coordinates for each axis in record is int(X) + record.x

Message ID	State	Bound To	Field Name		Field Type	Notes
0x20	Play	Client	X		Double
			Y		Double
			Z		Double
			Strength		Float	If the strength is greater or equal to 2.0, or the block interaction is not 0 (keep), large explosion particles are used. Otherwise, small explosion particles are used.
			Record Count		VarInt	Number of elements in the following array.
			Records		Array of (Byte, Byte, Byte)	Each record is 3 signed bytes long; the 3 bytes are the XYZ (respectively) signed offsets of affected blocks.
			Player Motion X		Float	X velocity of the player being pushed by the explosion.
			Player Motion Y		Float	Y velocity of the player being pushed by the explosion.
			Player Motion Z		Float	Z velocity of the player being pushed by the explosion.
			Block Interaction		VarInt Enum	0 = keep, 1 = destroy, 2 = destroy_with_decay, 3 = trigger_block.
			Small Explosion Particle ID		VarInt	The particle ID listed in Particles.
			Small Explosion Particle Data		Varies	Particle data as specified in Particles.
			Large Explosion Particle ID		VarInt	The particle ID listed in Particles.
			Large Explosion Particle Data		Varies	Particle data as specified in Particles.
			Explosion Sound	Sound Name	Identifier	The name of the sound played.
				Has Fixed Range	Optional Boolean	Whether is has fixed range.
				Range	Optional Float	The fixed range of the sound. Only present if previous boolean is true.

Unload Chunk

Tells the client to unload a chunk column.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x21	Play	Client	Chunk Z	Int	Block coordinate divided by 16, rounded down.
			Chunk X	Int	Block coordinate divided by 16, rounded down.

Note: The order is inverted, because the client reads this message as one big-endian Long, with Z being the upper 32 bits.

It is legal to send this message even if the given chunk is not currently loaded.

Game Event

Used for a wide variety of game events, from weather to bed use to game mode to demo messages.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Client	Event	Unsigned Byte	See below.
			Value	Float	Depends on Event.

Events:

Event	Effect	Value
0	No respawn block available	Note: Displays message 'block.minecraft.spawn.not_valid' (You have no home bed or charged respawn anchor, or it was obstructed) to the player.
1	Begin raining
2	End raining
3	Change game mode	0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
4	Win game	0: Just respawn player. 1: Roll the credits and respawn player. Note that 1 is only sent by notchian server when player has not yet achieved advancement "The end?", else 0 is sent.
5	Demo event	0: Show welcome to demo screen. 101: Tell movement controls. 102: Tell jump control. 103: Tell inventory control. 104: Tell that the demo is over and print a message about how to take a screenshot.
6	Arrow hit player	Note: Sent when any player is struck by an arrow.
7	Rain level change	Note: Seems to change both sky color and lighting. Rain level ranging from 0 to 1.
8	Thunder level change	Note: Seems to change both sky color and lighting (same as Rain level change, but doesn't start rain). It also requires rain to render by notchian client. Thunder level ranging from 0 to 1.
9	Play pufferfish sting sound
10	Play elder guardian mob appearance (effect and sound)
11	Enable respawn screen	0: Enable respawn screen. 1: Immediately respawn (sent when the doImmediateRespawn gamerule changes).
12	Limited crafting	0: Disable limited crafting. 1: Enable limited crafting (sent when the doLimitedCrafting gamerule changes).
13	Start waiting for level chunks	Instructs the client to begin the waiting process for the level chunks. Sent by the server after the level is cleared on the client and is being re-sent (either during the first, or subsequent reconfigurations).

Open Horse Screen

This message is used exclusively for opening the horse GUI. Open Screen is used for all other GUIs. The client will not open the inventory if the Entity ID does not point to an horse-like animal.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x23	Play	Client	Window ID	Unsigned Byte
			Slot count	VarInt
			Entity ID	Int

Hurt Animation

Plays a bobbing animation for the entity receiving damage.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x24	Play	Client
			Entity ID		VarInt		The ID of the entity taking damage
			Yaw		Float		The direction the damage is coming from in relation to the entity

Initialize World Border

Message ID	State	Bound To	Field Name	Field Type	Notes
0x25	Play	Client	X	Double
			Z	Double
			Old Diameter	Double	Current length of a single side of the world border, in meters.
			New Diameter	Double	Target length of a single side of the world border, in meters.
			Speed	VarLong	Number of real-time milliseconds until New Diameter is reached. It appears that Notchian server does not sync world border speed to game ticks, so it gets out of sync with server lag. If the world border is not moving, this is set to 0.
			Portal Teleport Boundary	VarInt	Resulting coordinates from a portal teleport are limited to ±value. Usually 29999984.
			Warning Blocks	VarInt	In meters.
			Warning Time	VarInt	In seconds as set by /worldborder warning time.

The Notchian client determines how solid to display the warning by comparing to whichever is higher, the warning distance or whichever is lower, the distance from the current diameter to the target diameter or the place the border will be after warningTime seconds. In pseudocode:

distance = max(min(resizeSpeed * 1000 * warningTime, abs(targetDiameter - currentDiameter)), warningDistance);
if (playerDistance < distance) {
    warning = 1.0 - playerDistance / distance;
} else {
    warning = 0.0;
}

Clientbound Keep Alive (play)

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same payload (see Serverbound Keep Alive). If the client does not respond to a Keep Alive message within 15 seconds after it was sent, the server kicks the client. Vice versa, if the server does not send any keep-alives for 20 seconds, the client will disconnect and yields a "Timed out" exception.

The Notchian server uses a system-dependent time in milliseconds to generate the keep alive ID value.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x26	Play	Client	Keep Alive ID	Long

Chunk Data and Update Light

Main article: Chunk Format

See also: #Unload Chunk

Sent when a chunk comes into the client's view distance, specifying its terrain, lighting and block entities.

The chunk must be within the view area previously specified with Set Center Chunk; see that message for details.

It is not strictly necessary to send all block entities in this message; it is still legal to send them with Block Entity Data later.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x27	Play	Client	Chunk X		Int		Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z		Int		Chunk coordinate (block coordinate divided by 16, rounded down)
			Heightmaps		NBT		See Chunk Format#Heightmaps structure
			Size		VarInt		Size of Data in bytes
			Data		Byte Array		See Chunk Format#Data structure
			Number of block entities		VarInt		Number of elements in the following array
			Block Entity	Packed XZ	Array	Unsigned Byte	The packed section coordinates are relative to the chunk they are in. Values 0-15 are valid. packed_xz = ((blockX & 15) << 4) | (blockZ & 15) // encode x = packed_xz >> 4, z = packed_xz & 15 // decode
				Y		Short	The height relative to the world
				Type		VarInt	The type of block entity
				Data		NBT	The block entity's data, without the X, Y, and Z values
			Sky Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Sky Light array below. The least significant bit is for blocks 16 blocks to 1 block below the min world height (one section below the world), while the most significant bit covers blocks 1 to 16 blocks above the max world height (one section above the world).
			Block Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Block Light array below. The order of bits is the same as in Sky Light Mask.
			Empty Sky Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Sky Light data. The order of bits is the same as in Sky Light Mask.
			Empty Block Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Block Light data. The order of bits is the same as in Sky Light Mask.
			Sky Light array count		VarInt		Number of entries in the following array; should match the number of bits set in Sky Light Mask
			Sky Light arrays	Length	Array	VarInt	Length of the following array in bytes (always 2048)
				Sky Light array		Byte Array (2048)	There is 1 array for each bit set to true in the sky light mask, starting with the lowest value. Half a byte per light value. Indexed ((y<<8) | (z<<4) | x) / 2 If there's a remainder, masked 0xF0 else 0x0F.
			Block Light array count		VarInt		Number of entries in the following array; should match the number of bits set in Block Light Mask
			Block Light arrays	Length	Array	VarInt	Length of the following array in bytes (always 2048)
				Block Light array		Byte Array (2048)	There is 1 array for each bit set to true in the block light mask, starting with the lowest value. Half a byte per light value. Indexed ((y<<8) | (z<<4) | x) / 2 If there's a remainder, masked 0xF0 else 0x0F.

Unlike the Update Light message which uses the same format, setting the bit corresponding to a section to 0 in both of the block light or sky light masks does not appear to be useful, and the results in testing have been highly inconsistent.

World Event

	The following information needs to be added to this page:
	The events listed below are not up-to-date with the latest release version, being either improperly documented or missing from the list altogether.

Sent when a client is to play a sound or particle effect.

By default, the Minecraft client adjusts the volume of sound effects based on distance. The final boolean field is used to disable this, and instead the effect is played from 2 blocks away in the correct direction. Currently this is only used for effect 1023 (wither spawn), effect 1028 (enderdragon death), and effect 1038 (end portal opening); it is ignored on other effects.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x28	Play	Client	Event	Int	The event, see below.
			Location	Position	The location of the event.
			Data	Int	Extra data for certain events, see below.
			Disable Relative Volume	Boolean	See above.

Events:

ID	Name	Data
Sound
1000	Dispenser dispenses
1001	Dispenser fails to dispense
1002	Dispenser shoots
1003	Ender eye launched
1004	Firework shot
1009	Fire extinguished
1010	Play record	An ID in the minecraft:item registry, corresponding to a record item. If the ID doesn't correspond to a record, the message is ignored. Any record already being played at the given location is overwritten. See Data Generators for information on item IDs.
1011	Stop record
1015	Ghast warns
1016	Ghast shoots
1017	Enderdragon shoots
1018	Blaze shoots
1019	Zombie attacks wood door
1020	Zombie attacks iron door
1021	Zombie breaks wood door
1022	Wither breaks block
1023	Wither spawned
1024	Wither shoots
1025	Bat takes off
1026	Zombie infects
1027	Zombie villager converted
1028	Ender dragon death
1029	Anvil destroyed
1030	Anvil used
1031	Anvil landed
1032	Portal travel
1033	Chorus flower grown
1034	Chorus flower died
1035	Brewing stand brewed
1038	End portal created in overworld
1039	Phantom bites
1040	Zombie converts to drowned
1041	Husk converts to zombie by drowning
1042	Grindstone used
1043	Book page turned
1044	Smithing table used
1045	Pointed dripstone landing
1046	Lava dripping on cauldron from dripstone
1047	Water dripping on cauldron from dripstone
1048	Skeleton converts to stray
1049	Crafter successfully crafts item
1050	Crafter fails to craft item
Particle
1500	Composter composts
1501	Lava converts block (either water to stone, or removes existing blocks such as torches)
1502	Redstone torch burns out
1503	Ender eye placed
1504	Fluid drips from dripstone
1505	Bonemeal particles	How many particles to spawn.
2000	Spawns 10 smoke particles, e.g. from a fire	Direction, see below.
2001	Block break + block break sound	Block state ID (see Chunk Format#Block state registry).
2002	Splash potion. Particle effect + glass break sound.	RGB color as an integer (e.g. 8364543 for #7FA1FF).
2003	Eye of Ender entity break animation — particles and sound
2004	Mob spawn particle effect: smoke + flames
2006	Dragon breath
2007	Instant splash potion. Particle effect + glass break sound.	RGB color as an integer (e.g. 8364543 for #7FA1FF).
2008	Ender dragon destroys block
2009	Wet sponge vaporizes in nether
3000	End gateway spawn
3001	Enderdragon growl
3002	Electric spark
3003	Copper apply wax
3004	Copper remove wax
3005	Copper scrape oxidation

Smoke directions:

ID	Direction
0	Down
1	Up
2	North
3	South
4	West
5	East

Particle

Displays the named particle

Message ID	State	Bound To	Field Name	Field Type	Notes
0x29	Play	Client	Long Distance	Boolean	If true, particle distance increases from 256 to 65536.
			X	Double	X position of the particle.
			Y	Double	Y position of the particle.
			Z	Double	Z position of the particle.
			Offset X	Float	This is added to the X position after being multiplied by random.nextGaussian().
			Offset Y	Float	This is added to the Y position after being multiplied by random.nextGaussian().
			Offset Z	Float	This is added to the Z position after being multiplied by random.nextGaussian().
			Max Speed	Float
			Particle Count	Int	The number of particles to create.
			Particle ID	VarInt	The particle ID listed in Particles.
			Data	Varies	Particle data as specified in Particles.

Update Light

Updates light levels for a chunk. See Light for information on how lighting works in Minecraft.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x2A	Play	Client	Chunk X		VarInt		Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z		VarInt		Chunk coordinate (block coordinate divided by 16, rounded down)
			Sky Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Sky Light array below. The least significant bit is for blocks 16 blocks to 1 block below the min world height (one section below the world), while the most significant bit covers blocks 1 to 16 blocks above the max world height (one section above the world).
			Block Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Block Light array below. The order of bits is the same as in Sky Light Mask.
			Empty Sky Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Sky Light data. The order of bits is the same as in Sky Light Mask.
			Empty Block Light Mask		BitSet		BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Block Light data. The order of bits is the same as in Sky Light Mask.
			Sky Light array count		VarInt		Number of entries in the following array; should match the number of bits set in Sky Light Mask
			Sky Light arrays	Length	Array	VarInt	Length of the following array in bytes (always 2048)
				Sky Light array		Byte Array (2048)	There is 1 array for each bit set to true in the sky light mask, starting with the lowest value. Half a byte per light value.
			Block Light array count		VarInt		Number of entries in the following array; should match the number of bits set in Block Light Mask
			Block Light arrays	Length	Array	VarInt	Length of the following array in bytes (always 2048)
				Block Light array		Byte Array (2048)	There is 1 array for each bit set to true in the block light mask, starting with the lowest value. Half a byte per light value.

A bit will never be set in both the block light mask and the empty block light mask, though it may be present in neither of them (if the block light does not need to be updated for the corresponding chunk section). The same applies to the sky light mask and the empty sky light mask.

Login (play)

	The following information needs to be added to this page:
	Although the number of portal cooldown ticks is included in this message, the whole portal usage process is still dictated entirely by the server. What kind of effect does this value have on the client, if any?

See Protocol Encryption for information on logging in.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2B	Play	Client	Entity ID	Int	The player's Entity ID (EID).
			Is hardcore	Boolean
			Dimension Count	VarInt	Size of the following array.
			Dimension Names	Array of Identifier	Identifiers for all dimensions on the server.
			Max Players	VarInt	Was once used by the client to draw the player list, but now is ignored.
			View Distance	VarInt	Render distance (2-32).
			Simulation Distance	VarInt	The distance that the client will process specific things, such as entities.
			Reduced Debug Info	Boolean	If true, a Notchian client shows reduced information on the debug screen. For servers in development, this should almost always be false.
			Enable respawn screen	Boolean	Set to false when the doImmediateRespawn gamerule is true.
			Do limited crafting	Boolean	Whether players can only craft recipes they have already unlocked. Currently unused by the client.
			Dimension Type	VarInt	The ID of the type of dimension in the minecraft:dimension_type registry, defined by the Registry Data message.
			Dimension Name	Identifier	Name of the dimension being spawned into.
			Hashed seed	Long	First 8 bytes of the SHA-256 hash of the world's seed. Used client side for biome noise
			Game mode	Unsigned Byte	0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
			Previous Game mode	Byte	-1: Undefined (null), 0: Survival, 1: Creative, 2: Adventure, 3: Spectator. The previous game mode. Vanilla client uses this for the debug (F3 + N & F3 + F4) game mode switch. (More information needed)
			Is Debug	Boolean	True if the world is a debug mode world; debug mode worlds cannot be modified and have predefined blocks.
			Is Flat	Boolean	True if the world is a superflat world; flat worlds have different void fog and a horizon at y=0 instead of y=63.
			Has death location	Boolean	If true, then the next two fields are present.
			Death dimension name	Optional Identifier	Name of the dimension the player died in.
			Death location	Optional Position	The location that the player died at.
			Portal cooldown	VarInt	The number of ticks until the player can use the portal again.
			Enforces Secure Chat	Boolean

Map Data

Updates a rectangular area on a map item.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x2C	Play	Client	Map ID		VarInt		Map ID of the map being modified
			Scale		Byte		From 0 for a fully zoomed-in map (1 block per pixel) to 4 for a fully zoomed-out map (16 blocks per pixel)
			Locked		Boolean		True if the map has been locked in a cartography table
			Has Icons		Boolean
			Icon Count		Optional VarInt		Number of elements in the following array. Only present if previous Boolean is true.
			Icon	Type	Optional Array	VarInt Enum	See below
				X		Byte	Map coordinates: -128 for furthest left, +127 for furthest right
				Z		Byte	Map coordinates: -128 for highest, +127 for lowest
				Direction		Byte	0-15
				Has Display Name		Boolean
				Display Name		Optional Text Component	Only present if previous Boolean is true
			Color Patch	Columns	Unsigned Byte		Number of columns updated
				Rows	Optional Unsigned Byte		Only if Columns is more than 0; number of rows updated
				X	Optional Unsigned Byte		Only if Columns is more than 0; x offset of the westernmost column
				Z	Optional Unsigned Byte		Only if Columns is more than 0; z offset of the northernmost row
				Length	Optional VarInt		Only if Columns is more than 0; length of the following array
				Data	Optional Array of Unsigned Byte		Only if Columns is more than 0; see Map item format

For icons, a direction of 0 is a vertical icon and increments by 22.5° (360/16).

Types are based off of rows and columns in map_icons.png:

Icon type	Result
0	White arrow (players)
1	Green arrow (item frames)
2	Red arrow
3	Blue arrow
4	White cross
5	Red pointer
6	White circle (off-map players)
7	Small white circle (far-off-map players)
8	Mansion
9	Monument
10	White Banner
11	Orange Banner
12	Magenta Banner
13	Light Blue Banner
14	Yellow Banner
15	Lime Banner
16	Pink Banner
17	Gray Banner
18	Light Gray Banner
19	Cyan Banner
20	Purple Banner
21	Blue Banner
22	Brown Banner
23	Green Banner
24	Red Banner
25	Black Banner
26	Treasure marker

Merchant Offers

The list of trades a villager NPC is offering.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x2D	Play	Client	Window ID		VarInt		The ID of the window that is open; this is an int rather than a byte.
			Size		VarInt		The number of trades in the following array.
			Trades	Input item 1	Array	Trade Item	See below. The first item the player has to supply for this villager trade. The count of the item stack is the default "price" of this trade.
				Output item		Slot	The item the player will receive from this villager trade.
				Input item 2		Optional Trade Item	The second item the player has to supply for this villager trade. May be an empty slot.
				Trade disabled		Boolean	True if the trade is disabled; false if the trade is enabled.
				Number of trade uses		Int	Number of times the trade has been used so far. If equal to the maximum number of trades, the client will display a red X.
				Maximum number of trade uses		Int	Number of times this trade can be used before it's exhausted.
				XP		Int	Amount of XP the villager will earn each time the trade is used.
				Special Price		Int	Can be zero or negative. The number is added to the price when an item is discounted due to player reputation or other effects.
				Price Multiplier		Float	Can be low (0.05) or high (0.2). Determines how much demand, player reputation, and temporary effects will adjust the price.
				Demand		Int	If positive, causes the price to increase. Negative values seem to be treated the same as zero.
			Villager level		VarInt		Appears on the trade GUI; meaning comes from the translation key merchant.level. + level. 1: Novice, 2: Apprentice, 3: Journeyman, 4: Expert, 5: Master.
			Experience		VarInt		Total experience for this villager (always 0 for the wandering trader).
			Is regular villager		Boolean		True if this is a regular villager; false for the wandering trader. When false, hides the villager level and some other GUI elements.
			Can restock		Boolean		True for regular villagers and false for the wandering trader. If true, the "Villagers restock up to two times per day." message is displayed when hovering over disabled trades.

Trade Item:

Field Name	Field Type			Meaning
Item ID	VarInt			The item ID. Item IDs are distinct from block IDs; see Data Generators for more information.
Item Count	VarInt			The item count.
Size	VarInt			The number of components in the following array.
Components	Component type	Array	VarInt Enum	The type of component. See Structured components for more detail.
	Component data		Varies	The component-dependent data. See Structured components for more detail.

Modifiers can increase or decrease the number of items for the first input slot. The second input slot and the output slot never change the number of items. The number of items may never be less than 1, and never more than the stack size. If special price and demand are both zero, only the default price is displayed. If either is non-zero, then the adjusted price is displayed next to the crossed-out default price. The adjusted prices is calculated as follows:

Adjusted price = default price + floor(default price x multiplier x demand) + special price

The merchant UI, for reference

Update Entity Position

This message is sent by the server when an entity moves a small distance. The change in position is represented as a fixed-point number with 12 fraction bits and 4 integer bits. As such, the maximum movement distance along each axis is 8 blocks in the negative direction, or 7.999755859375 blocks in the positive direction. If the movement exceeds these limits, Teleport Entity should be sent instead.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2E	Play	Client	Entity ID	VarInt
			Delta X	Short	Change in X position as currentX * 4096 - prevX * 4096.
			Delta Y	Short	Change in Y position as currentY * 4096 - prevY * 4096.
			Delta Z	Short	Change in Z position as currentZ * 4096 - prevZ * 4096.
			On Ground	Boolean

Update Entity Position and Rotation

This message is sent by the server when an entity rotates and moves. See #Update Entity Position for how the position is encoded.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2F	Play	Client	Entity ID	VarInt
			Delta X	Short	Change in X position as currentX * 4096 - prevX * 4096.
			Delta Y	Short	Change in Y position as currentY * 4096 - prevY * 4096.
			Delta Z	Short	Change in Z position as currentZ * 4096 - prevZ * 4096.
			Yaw	Angle	New angle, not a delta.
			Pitch	Angle	New angle, not a delta.
			On Ground	Boolean

Update Entity Rotation

This message is sent by the server when an entity rotates.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x30	Play	Client	Entity ID	VarInt
			Yaw	Angle	New angle, not a delta.
			Pitch	Angle	New angle, not a delta.
			On Ground	Boolean

Move Vehicle

Note that all fields use absolute positioning and do not allow for relative positioning.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x31	Play	Client	X	Double	Absolute position (X coordinate).
			Y	Double	Absolute position (Y coordinate).
			Z	Double	Absolute position (Z coordinate).
			Yaw	Float	Absolute rotation on the vertical axis, in degrees.
			Pitch	Float	Absolute rotation on the horizontal axis, in degrees.

Open Book

Sent when a player right clicks with a signed book. This tells the client to open the book GUI.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x32	Play	Client	Hand	VarInt Enum	0: Main hand, 1: Off hand .

Open Screen

This is sent to the client when it should open an inventory, such as a chest, workbench, furnace, or other container. Resending this message with already existing window id, will update the window title and window type without closing the window.

This message is not sent to clients opening their own inventory, nor do clients inform the server in any way when doing so. From the server's perspective, the inventory is always "open" whenever no other windows are.

For horses, use Open Horse Screen.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x33	Play	Client	Window ID	VarInt	An identifier for the window to be displayed. Notchian server implementation is a counter, starting at 1. There can only be one window at a time; this is only used to ignore outdated messages targeting already-closed windows. Note also that the Window ID field in most other messages is only a single byte, and indeed, the Notchian server wraps around after 100.
			Window Type	VarInt	The window type to use for display. Contained in the minecraft:menu registry; see Inventory for the different values.
			Window Title	Text Component	The title of the window.

Open Sign Editor

Sent when the client has placed a sign and is allowed to send Update Sign. There must already be a sign at the given location (which the client does not do automatically) - send a Block Update first.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x34	Play	Client	Location	Position
			Is Front Text	Boolean	Whether the opened editor is for the front or on the back of the sign

Ping (play)

Message is not used by the Notchian server. When sent to the client, client responds with a Pong message with the same id.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x35	Play	Client	ID	Int

Ping Response (play)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x36	Play	Client	Payload	Long	Should be the same as sent by the client.

Place Ghost Recipe

Response to the serverbound message (Place Recipe), with the same recipe ID. Appears to be used to notify the UI.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x37	Play	Client	Window ID	Byte
			Recipe	Identifier	A recipe ID.

Player Abilities (clientbound)

The latter 2 floats are used to indicate the flying speed and field of view respectively, while the first byte is used to determine the value of 4 booleans.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x38	Play	Client	Flags	Byte	Bit field, see below.
			Flying Speed	Float	0.05 by default.
			Field of View Modifier	Float	Modifies the field of view, like a speed potion. A Notchian server will use the same value as the movement speed sent in the Update Attributes message, which defaults to 0.1 for players.

About the flags:

Field	Bit
Invulnerable	0x01
Flying	0x02
Allow Flying	0x04
Creative Mode (Instant Break)	0x08

Player Chat Message

Main article: Chat

Sends the client a chat message from a player.

Currently a lot is unknown about this message, blank descriptions are for those that are unknown

Message ID	State	Bound To	Sector	Field Name		Field Type	Notes
0x39	Play	Client	Header	Sender		UUID	Used by the Notchian client for the disableChat launch option. Setting both longs to 0 will always display the message regardless of the setting.
				Index		VarInt
				Message Signature Present		Boolean	States if a message signature is present
				Message Signature bytes		Optional Byte Array (256)	Only present if Message Signature Present is true. Cryptography, the signature consists of the Sender UUID, Session UUID from the Player Session message, Index, Salt, Timestamp in epoch seconds, the length of the original chat content, the original content itself, the length of Previous Messages, and all of the Previous message signatures. These values are hashed with SHA-256 and signed using the RSA cryptosystem. Modifying any of these values in the message will cause this signature to fail. This buffer is always 256 bytes long and it is not length-prefixed.
			Body	Message		String (256)	Raw (optionally) signed sent message content. This is used as the content parameter when formatting the message on the client.
				Timestamp		Long	Represents the time the message was signed as milliseconds since the epoch, used to check if the message was received within 2 minutes of it being sent.
				Salt		Long	Cryptography, used for validating the message signature.
			Previous Messages	Total Previous Messages		VarInt	The maximum length is 20 in Notchian client.
				Array (20)	Message ID	VarInt	The message Id + 1, used for validating message signature. The next field is present only when value of this field is equal to 0.
					Signature	Optional Byte Array (256)	The previous message's signature. Contains the same type of data as Message Signature bytes (256 bytes) above. Not length-prefxied.
			Other	Unsigned Content Present		Boolean	True if the next field is present
				Unsigned Content		Optional Text Component
				Filter Type		VarInt Enum	If the message has been filtered
				Filter Type Bits		Optional BitSet	Only present if the Filter Type is Partially Filtered. Specifies the indexes at which characters in the original message string should be replaced with the # symbol (i.e. filtered) by the Notchian client
			Chat Formatting	Chat Type		VarInt	The type of chat in the minecraft:chat_type registry, defined by the Registry Data message. This should not be 0, meaning it is likely index+1
				Sender Name		Text Component	The name of the one sending the message, usually the sender's display name. This is used as the sender parameter when formatting the message on the client.
				Has Target Name		Boolean	True if target name is present.
				Target Name		Optional Text Component	The name of the one receiving the message, usually the receiver's display name. Only present if previous boolean is true. This is used as the target parameter when formatting the message on the client.

Player Chat Handling Logic

Filter Types:

The filter type mask should NOT be specified unless partially filtered is selected

ID	Name	Description
0	PASS_THROUGH	Message is not filtered at all
1	FULLY_FILTERED	Message is fully filtered
2	PARTIALLY_FILTERED	Only some characters in the message are filtered

End Combat

Unused by the Notchian client. This data was once used for twitch.tv metadata circa 1.8.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x3A	Play	Client	Duration	VarInt	Length of the combat in ticks.

Enter Combat

Unused by the Notchian client. This data was once used for twitch.tv metadata circa 1.8.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x3B	Play	Client	no fields

Combat Death

Used to send a respawn screen.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x3C	Play	Client	Player ID	VarInt	Entity ID of the player that died (should match the client's entity ID).
			Message	Text Component	The death message.

Player Info Remove

Used by the server to remove players from the player list.

Message ID	State	Bound To	Field Name		Field Type	Notes
0x3D	Play	Client	Number of Players		VarInt	Number of elements in the following array.
			Player	Player Id	Array of UUID	UUIDs of players to remove.

Player Info Update

Sent by the server to update the user list (<tab> in the client).

Message ID	State	Bound To	Field Name		Field Type		Notes
0x3E	Play	Client	Actions		Byte		Determines what actions are present.
			Number Of Players		VarInt		Number of elements in the following array.
			Players	UUID	Array	UUID	The player UUID
				Player Actions		Array of Player Actions	The length of this array is determined by the number of Player Actions that give a non-zero value when applying its mask to the actions flag. For example given the decimal number 5, binary 00000101. The masks 0x01 and 0x04 would return a non-zero value, meaning the Player Actions array would include two actions: Add Player and Update Game Mode.

Player Actions

Action	Mask	Field Name		Type		Notes
Add Player	0x01	Name		String (16)
		Number Of Properties		VarInt		Number of elements in the following array.
		Property	Name	Array	String (32767)
			Value		String (32767)
			Is Signed		Boolean
			Signature		Optional String (32767)	Only if Is Signed is true.
Initialize Chat	0x02	Has Signature Data		Boolean
		Chat session ID		UUID		Only sent if Has Signature Data is true.
		Public key expiry time		Long		Key expiry time, as a UNIX timestamp in milliseconds. Only sent if Has Signature Data is true.
		Encoded public key size		VarInt		Size of the following array. Only sent if Has Signature Data is true. Maximum length is 512 bytes.
		Encoded public key		Byte Array (512)		The player's public key, in bytes. Only sent if Has Signature Data is true.
		Public key signature size		VarInt		Size of the following array. Only sent if Has Signature Data is true. Maximum length is 4096 bytes.
		Public key signature		Byte Array (4096)		The public key's digital signature. Only sent if Has Signature Data is true.
Update Game Mode	0x04	Game Mode		VarInt
Update Listed	0x08	Listed		Boolean		Whether the player should be listed on the player list.
Update Latency	0x10	Ping		VarInt		Measured in milliseconds.
Update Display Name	0x20	Has Display Name		Boolean
		Display Name		Optional Text Component		Only sent if Has Display Name is true.

The properties included in this message are the same as in Login Success, for the current player.

Ping values correspond with icons in the following way:

• A ping that negative (i.e. not known to the server yet) will result in the no connection icon.
• A ping under 150 milliseconds will result in 5 bars
• A ping under 300 milliseconds will result in 4 bars
• A ping under 600 milliseconds will result in 3 bars
• A ping under 1000 milliseconds (1 second) will result in 2 bars
• A ping greater than or equal to 1 second will result in 1 bar.

Look At

Used to rotate the client player to face the given location or entity (for /teleport [<targets>] <x> <y> <z> facing).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x3F	Play	Client
			Feet/eyes	VarInt Enum	Values are feet=0, eyes=1. If set to eyes, aims using the head position; otherwise aims using the feet position.
			Target x	Double	x coordinate of the point to face towards.
			Target y	Double	y coordinate of the point to face towards.
			Target z	Double	z coordinate of the point to face towards.
			Is entity	Boolean	If true, additional information about an entity is provided.
			Entity ID	Optional VarInt	Only if is entity is true — the entity to face towards.
			Entity feet/eyes	Optional VarInt Enum	Whether to look at the entity's eyes or feet. Same values and meanings as before, just for the entity's head/feet.

If the entity given by entity ID cannot be found, this message should be treated as if is entity was false.

Synchronize Player Position

Teleports the client, e.g. during login, when using an ender pearl, in response to invalid move messages, etc.

Due to latency, the server may receive outdated movement messages sent before the client was aware of the teleport. To account for this, the server ignores all movement messages from the client until a Confirm Teleportation message with an ID matching the one sent in the teleport message is received.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0, -1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360 (see MC-90097).

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x40	Play	Client	X	Double	Absolute or relative position, depending on Flags.
			Y	Double	Absolute or relative position, depending on Flags.
			Z	Double	Absolute or relative position, depending on Flags.
			Yaw	Float	Absolute or relative rotation on the X axis, in degrees.
			Pitch	Float	Absolute or relative rotation on the Y axis, in degrees.
			Flags	Byte	Reference the Flags table below. When the value of the this byte masked is zero the field is absolute, otherwise relative.
			Teleport ID	VarInt	Client should confirm this message with Confirm Teleportation containing the same Teleport ID.

Flags

Field	Hex Mask
X	0x01
Y	0x02
Z	0x04
Y_ROT (Pitch)	0x08
X_ROT (Yaw)	0x10

Update Recipe Book

Message ID	State	Bound To	Field Name	Field Type	Notes
0x41	Play	Client
			Action	VarInt	0: init, 1: add, 2: remove.
			Crafting Recipe Book Open	Boolean	If true, then the crafting recipe book will be open when the player opens its inventory.
			Crafting Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Smelting Recipe Book Open	Boolean	If true, then the smelting recipe book will be open when the player opens its inventory.
			Smelting Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Blast Furnace Recipe Book Open	Boolean	If true, then the blast furnace recipe book will be open when the player opens its inventory.
			Blast Furnace Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Smoker Recipe Book Open	Boolean	If true, then the smoker recipe book will be open when the player opens its inventory.
			Smoker Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Array size 1	VarInt	Number of elements in the following array.
			Recipe IDs	Array of Identifier
			Array size 2	Optional VarInt	Number of elements in the following array, only present if action is 0 (init).
			Recipe IDs	Optional Array of Identifier	Only present if mode is 0 (init)

Action:

• 0 (init) = All the recipes in list 1 will be tagged as displayed, and all the recipes in list 2 will be added to the recipe book. Recipes that aren't tagged will be shown in the notification.
• 1 (add) = All the recipes in the list are added to the recipe book and their icons will be shown in the notification.
• 2 (remove) = Remove all the recipes in the list. This allows them to be re-displayed when they are re-added.

Remove Entities

Sent by the server when an entity is to be destroyed on the client.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x42	Play	Client	Count	VarInt	Number of elements in the following array.
			Entity IDs	Array of VarInt	The list of entities to destroy.

Remove Entity Effect

Message ID	State	Bound To	Field Name	Field Type	Notes
0x43	Play	Client	Entity ID	VarInt
			Effect ID	VarInt	See this table.

Reset Score

This is sent to the client when it should remove a scoreboard item.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x44	Play	Client	Entity Name	String (32767)	The entity whose score this is. For players, this is their username; for other entities, it is their UUID.
			Has Objective Name	Boolean	Whether the score should be removed for the specified objective, or for all of them.
			Objective Name	Optional String (32767)	The name of the objective the score belongs to. Only present if the previous field is true.

Remove Resource Pack (play)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x45	Play	Client	Has UUID	Boolean	Whether a specific resource pack should be removed, or all of them.
			UUID	Optional UUID	The UUID of the resource pack to be removed. Only present if the previous field is true.

Add Resource Pack (play)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x46	Play	Client	UUID	UUID	The unique identifier of the resource pack.
			URL	String (32767)	The URL to the resource pack.
			Hash	String (40)	A 40 character hexadecimal, case-insensitive SHA-1 hash of the resource pack file. If it's not a 40 character hexadecimal string, the client will not use it for hash verification and likely waste bandwidth.
			Forced	Boolean	The Notchian client will be forced to use the resource pack from the server. If they decline they will be kicked from the server.
			Has Prompt Message	Boolean	Whether a custom message should be used on the resource pack prompt.
			Prompt Message	Optional Text Component	This is shown in the prompt making the client accept or decline the resource pack. Only present if the previous field is true.

Respawn

	The following information needs to be added to this page:
	Although the number of portal cooldown ticks is included in this message, the whole portal usage process is still dictated entirely by the server. What kind of effect does this value have on the client, if any?

To change the player's dimension (overworld/nether/end), send them a respawn message with the appropriate dimension, followed by prechunks/chunks for the new dimension, and finally a position and look message. You do not need to unload chunks, the client will do it automatically.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x47	Play	Client	Dimension Type	VarInt	The ID of type of dimension in the minecraft:dimension_type registry, defined by the Registry Data message.
			Dimension Name	Identifier	Name of the dimension being spawned into.
			Hashed seed	Long	First 8 bytes of the SHA-256 hash of the world's seed. Used client side for biome noise
			Game mode	Unsigned Byte	0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
			Previous Game mode	Byte	-1: Undefined (null), 0: Survival, 1: Creative, 2: Adventure, 3: Spectator. The previous game mode. Vanilla client uses this for the debug (F3 + N & F3 + F4) game mode switch. (More information needed)
			Is Debug	Boolean	True if the world is a debug mode world; debug mode worlds cannot be modified and have predefined blocks.
			Is Flat	Boolean	True if the world is a superflat world; flat worlds have different void fog and a horizon at y=0 instead of y=63.
			Has death location	Boolean	If true, then the next two fields are present.
			Death dimension Name	Optional Identifier	Name of the dimension the player died in.
			Death location	Optional Position	The location that the player died at.
			Portal cooldown	VarInt	The number of ticks until the player can use the portal again.
			Data kept	Byte	Bit mask. 0x01: Keep attributes, 0x02: Keep metadata. Tells which data should be kept on the client side once the player has respawned. In the Notchian implementation, this is context dependent: normal respawns (after death) keep no data; exiting the end poem/credits keeps the attributes; other dimension changes (portals or teleports) keep all data.

Avoid changing player's dimension to same dimension they were already in unless they are dead. If you change the dimension to one they are already in, weird bugs can occur, such as the player being unable to attack other players in new world (until they die and respawn).

Before 1.16, if you must respawn a player in the same dimension without killing them, send two respawn messages, one to a different world and then another to the world you want. You do not need to complete the first respawn; it only matters that you send two messages.

Set Head Rotation

Changes the direction an entity's head is facing.

While sending the Entity Look message changes the vertical rotation of the head, sending this message appears to be necessary to rotate the head horizontally.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x48	Play	Client	Entity ID	VarInt
			Head Yaw	Angle	New angle, not a delta.

Update Section Blocks

Fired whenever 2 or more blocks are changed within the same chunk on the same tick.

Changing blocks in chunks not loaded by the client is unsafe (see note on Block Update).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x49	Play	Client	Chunk section position	Long	Chunk section coordinate (encoded chunk x and z with each 22 bits, and section y with 20 bits, from left to right).
			Blocks array size	VarInt	Number of elements in the following array.
			Blocks	Array of VarLong	Each entry is composed of the block state id, shifted left by 12, and the relative block position in the chunk section (4 bits for x, z, and y, from left to right).

Chunk section position is encoded:

((sectionX & 0x3FFFFF) << 42) | (sectionY & 0xFFFFF) | ((sectionZ & 0x3FFFFF) << 20);

and decoded:

sectionX = long >> 42;
sectionY = long << 44 >> 44;
sectionZ = long << 22 >> 42;

Blocks are encoded:

blockStateId << 12 | (blockLocalX << 8 | blockLocalZ << 4 | blockLocalY)
//Uses the local position of the given block position relative to its respective chunk section

and decoded:

blockStateId = long >> 12;
blockLocalX = (long >> 8) & 0xF;
blockLocalY = long & 0xF;
blockLocalZ = (long >> 4) & 0xF;

Select Advancements Tab

Sent by the server to indicate that the client should switch advancement tab. Sent either when the client switches tab in the GUI or when an advancement in another tab is made.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x4A	Play	Client	Has id	Boolean	Indicates if the next field is present.
			Identifier	Optional Identifier	See below.

The Identifier can be one of the following:

Identifier
minecraft:story/root
minecraft:nether/root
minecraft:end/root
minecraft:adventure/root
minecraft:husbandry/root

If no or an invalid identifier is sent, the client will switch to the first tab in the GUI.

Server Data

Message ID	State	Bound To	Field Name	Field Type	Notes
0x4B	Play	Client	MOTD	Text Component
			Has Icon	Boolean
			Size	Optional VarInt	Number of bytes in the following array. Only present if Has Icon is true.
			Icon	Optional Byte Array	Icon bytes in the PNG format. Only present is Has Icon is true.

Set Action Bar Text

Displays a message above the hotbar. Equivalent to System Chat Message with Overlay set to true, except that chat message blocking isn't performed. Used by the Notchian server only to implement the /title command.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x4C	Play	Client	Action bar text	Text Component

Set Border Center

Message ID	State	Bound To	Field Name	Field Type	Notes
0x4D	Play	Client	X	Double
			Z	Double

Set Border Lerp Size

Message ID	State	Bound To	Field Name	Field Type	Notes
0x4E	Play	Client	Old Diameter	Double	Current length of a single side of the world border, in meters.
			New Diameter	Double	Target length of a single side of the world border, in meters.
			Speed	VarLong	Number of real-time milliseconds until New Diameter is reached. It appears that Notchian server does not sync world border speed to game ticks, so it gets out of sync with server lag. If the world border is not moving, this is set to 0.

Set Border Size

Message ID	State	Bound To	Field Name	Field Type	Notes
0x4F	Play	Client	Diameter	Double	Length of a single side of the world border, in meters.

Set Border Warning Delay

Message ID	State	Bound To	Field Name	Field Type	Notes
0x50	Play	Client	Warning Time	VarInt	In seconds as set by /worldborder warning time.

Set Border Warning Distance

Message ID	State	Bound To	Field Name	Field Type	Notes
0x51	Play	Client	Warning Blocks	VarInt	In meters.

Set Camera

Sets the entity that the player renders from. This is normally used when the player left-clicks an entity while in spectator mode.

The player's camera will move with the entity and look where it is looking. The entity is often another player, but can be any type of entity. The player is unable to move this entity (move messages will act as if they are coming from the other entity).

If the given entity is not loaded by the player, this message is ignored. To return control to the player, send this message with their entity ID.

The Notchian server resets this (sends it back to the default entity) whenever the spectated entity is killed or the player sneaks, but only if they were spectating an entity. It also sends this message whenever the player switches out of spectator mode (even if they weren't spectating an entity).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x52	Play	Client	Camera ID	VarInt	ID of the entity to set the client's camera to.

The notchian client also loads certain shaders for given entities:

• Creeper → shaders/post/creeper.json
• Spider (and cave spider) → shaders/post/spider.json
• Enderman → shaders/post/invert.json
• Anything else → the current shader is unloaded

Set Held Item (clientbound)

Sent to change the player's slot selection.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x53	Play	Client	Slot	Byte	The slot which the player has selected (0–8).

Set Center Chunk

Sets the center position of the client's chunk loading area. The area is square-shaped, spanning 2 × server view distance + 7 chunks on both axes (width, not radius!). Since the area's width is always an odd number, there is no ambiguity as to which chunk is the center.

The Notchian client ignores attempts to send chunks located outside the loading area, and immediately unloads any existing chunks no longer inside it.

The center chunk is normally the chunk the player is in, but apart from the implications on chunk loading, the (Notchian) client takes no issue with this not being the case. Indeed, as long as chunks are sent only within the default loading area centered on the world origin, it is not necessary to send this message at all. This may be useful for servers with small bounded worlds, such as minigames, since it ensures chunks never need to be resent after the client has joined, saving on bandwidth.

The Notchian server sends this message whenever the player moves across a chunk border horizontally, and also (according to testing) for any integer change in the vertical axis, even if it doesn't go across a chunk section border.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x54	Play	Client	Chunk X	VarInt	Chunk X coordinate of the loading area center.
			Chunk Z	VarInt	Chunk Z coordinate of the loading area center.

Set Render Distance

Sent by the integrated singleplayer server when changing render distance. This message is sent by the server when the client reappears in the overworld after leaving the end.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x55	Play	Client	View Distance	VarInt	Render distance (2-32).

Set Default Spawn Position

Sent by the server after login to specify the coordinates of the spawn point (the point at which players spawn at, and which the compass points to). It can be sent at any time to update the point compasses point at.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x56	Play	Client	Location	Position	Spawn location.
			Angle	Float	The angle at which to respawn at.

Display Objective

This is sent to the client when it should display a scoreboard.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x57	Play	Client	Position	VarInt	The position of the scoreboard. 0: list, 1: sidebar, 2: below name, 3 - 18: team specific sidebar, indexed as 3 + team color.
			Score Name	String (32767)	The unique name for the scoreboard to be displayed.

Set Entity Metadata

Updates one or more metadata properties for an existing entity. Any properties not included in the Metadata field are left unchanged.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x58	Play	Client	Entity ID	VarInt
			Metadata	Entity Metadata

Link Entities

This message is sent when an entity has been leashed to another entity.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x59	Play	Client	Attached Entity ID	Int	Attached entity's EID.
			Holding Entity ID	Int	ID of the entity holding the lead. Set to -1 to detach.

Set Entity Velocity

Velocity is in units of 1/8000 of a block per server tick (50ms); for example, -1343 would move (-1343 / 8000) = −0.167875 blocks per tick (or −3.3575 blocks per second).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x5A	Play	Client	Entity ID	VarInt
			Velocity X	Short	Velocity on the X axis.
			Velocity Y	Short	Velocity on the Y axis.
			Velocity Z	Short	Velocity on the Z axis.

Set Equipment

Message ID	State	Bound To	Field Name		Field Type		Notes
0x5B	Play	Client	Entity ID		VarInt		Entity's ID.
			Equipment	Slot	Array	Byte Enum	Equipment slot (see below). Also has the top bit set if another entry follows, and otherwise unset if this is the last item in the array.
				Item		Slot

Equipment slot can be one of the following:

ID	Equipment slot
0	Main hand
1	Off hand
2	Boots
3	Leggings
4	Chestplate
5	Helmet
6	Body

Set Experience

Sent by the server when the client should change experience levels.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x5C	Play	Client	Experience bar	Float	Between 0 and 1.
			Level	VarInt
			Total Experience	VarInt	See Experience#Leveling up on the Minecraft Wiki for Total Experience to Level conversion.

Set Health

Sent by the server to set the health of the player it is sent to.

Food saturation acts as a food “overcharge”. Food values will not decrease while the saturation is over zero. New players logging in or respawning automatically get a saturation of 5.0. Eating food increases the saturation as well as the food bar.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x5D	Play	Client	Health	Float	0 or less = dead, 20 = full HP.
			Food	VarInt	0–20.
			Food Saturation	Float	Seems to vary from 0.0 to 5.0 in integer increments.

Update Objectives

This is sent to the client when it should create a new scoreboard objective or remove one.

Message ID	State	Bound To	Field Name		Field Type	Notes
0x5E	Play	Client	Objective Name		String (32767)	A unique name for the objective.
			Mode		Byte	0 to create the scoreboard. 1 to remove the scoreboard. 2 to update the display text.
			Objective Value		Optional Text Component	Only if mode is 0 or 2.The text to be displayed for the score.
			Type		Optional VarInt Enum	Only if mode is 0 or 2. 0 = "integer", 1 = "hearts".
			Has Number Format		Optional Boolean	Only if mode is 0 or 2. Whether this objective has a set number format for the scores.
			Number Format		Optional VarInt Enum	Only if mode is 0 or 2 and the previous boolean is true. Determines how the score number should be formatted.
			Number Format	Field Name
			0: blank	no fields		Show nothing.
			1: styled	Styling	Compound Tag	The styling to be used when formatting the score number. Contains the text component styling fields.
			2: fixed	Content	Text Component	The text to be used as placeholder.

Set Passengers

Message ID	State	Bound To	Field Name	Field Type	Notes
0x5F	Play	Client	Entity ID	VarInt	Vehicle's EID.
			Passenger Count	VarInt	Number of elements in the following array.
			Passengers	Array of VarInt	EIDs of entity's passengers.

Update Teams

Creates and updates teams.

Message ID	State	Bound To	Field Name		Field Type	Notes
0x60	Play	Client	Team Name		String (32767)	A unique name for the team. (Shared with scoreboard).
			Method		Byte	Determines the layout of the remaining message.
			0: create team	Team Display Name	Text Component
				Friendly Flags	Byte	Bit mask. 0x01: Allow friendly fire, 0x02: can see invisible players on same team.
				Name Tag Visibility	String Enum (40)	always, hideForOtherTeams, hideForOwnTeam, never.
				Collision Rule	String Enum (40)	always, pushOtherTeams, pushOwnTeam, never.
				Team Color	VarInt Enum	Used to color the name of players on the team; see below.
				Team Prefix	Text Component	Displayed before the names of players that are part of this team.
				Team Suffix	Text Component	Displayed after the names of players that are part of this team.
				Entity Count	VarInt	Number of elements in the following array.
				Entities	Array of String (32767)	Identifiers for the entities in this team. For players, this is their username; for other entities, it is their UUID.
			1: remove team	no fields	no fields
			2: update team info	Team Display Name	Text Component
				Friendly Flags	Byte	Bit mask. 0x01: Allow friendly fire, 0x02: can see invisible entities on same team.
				Name Tag Visibility	String Enum (40)	always, hideForOtherTeams, hideForOwnTeam, never
				Collision Rule	String Enum (40)	always, pushOtherTeams, pushOwnTeam, never
				Team Color	VarInt Enum	Used to color the name of players on the team; see below.
				Team Prefix	Text Component	Displayed before the names of players that are part of this team.
				Team Suffix	Text Component	Displayed after the names of players that are part of this team.
			3: add entities to team	Entity Count	VarInt	Number of elements in the following array.
				Entities	Array of String (32767)	Identifiers for the added entities. For players, this is their username; for other entities, it is their UUID.
			4: remove entities from team	Entity Count	VarInt	Number of elements in the following array.
				Entities	Array of String (32767)	Identifiers for the removed entities. For players, this is their username; for other entities, it is their UUID.

Team Color: The color of a team defines how the names of the team members are visualized; any formatting code can be used. The following table lists all the possible values.

ID	Formatting
0-15	Color formatting, same values as in Text formatting#Colors.
16	Obfuscated
17	Bold
18	Strikethrough
19	Underlined
20	Italic
21	Reset

Update Score

This is sent to the client when it should update a scoreboard item.

Message ID	State	Bound To	Field Name		Field Type	Notes
0x61	Play	Client	Entity Name		String (32767)	The entity whose score this is. For players, this is their username; for other entities, it is their UUID.
			Objective Name		String (32767)	The name of the objective the score belongs to.
			Value		VarInt	The score to be displayed next to the entry.
			Has Display Name		Boolean	Whether this score has a custom display name.
			Display Name		Optional Text Component	The custom display name. Only present if the previous boolean is true.
			Has Number Format		Boolean	Whether this score has a set number format. This overrides the number format set on the objective, if any.
			Number Format		Optional VarInt Enum	Determines how the score number should be formatted. Only present if the previous boolean is true.
			Number Format	Field Name
			0: blank	no fields		Show nothing.
			1: styled	Styling	Compound Tag	The styling to be used when formatting the score number. Contains the text component styling fields.
			2: fixed	Content	Text Component	The text to be used as placeholder.

Set Simulation Distance

Message ID	State	Bound To	Field Name	Field Type	Notes
0x62	Play	Client	Simulation Distance	VarInt	The distance that the client will process specific things, such as entities.

Set Subtitle Text

Message ID	State	Bound To	Field Name	Field Type	Notes
0x63	Play	Client	Subtitle Text	Text Component

Update Time

Time is based on ticks, where 20 ticks happen every second. There are 24000 ticks in a day, making Minecraft days exactly 20 minutes long.

The time of day is based on the timestamp modulo 24000. 0 is sunrise, 6000 is noon, 12000 is sunset, and 18000 is midnight.

The default SMP server increments the time by 20 every second.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x64	Play	Client	World Age	Long	In ticks; not changed by server commands.
			Time of day	Long	The world (or region) time, in ticks. If negative the sun will stop moving at the Math.abs of the time.

Set Title Text

Message ID	State	Bound To	Field Name	Field Type	Notes
0x65	Play	Client	Title Text	Text Component

Set Title Animation Times

Message ID	State	Bound To	Field Name	Field Type	Notes
0x66	Play	Client	Fade In	Int	Ticks to spend fading in.
			Stay	Int	Ticks to keep the title displayed.
			Fade Out	Int	Ticks to spend fading out, not when to start fading out.

Entity Sound Effect

Plays a sound effect from an entity, either by hardcoded ID or Identifier. Sound IDs and names can be found here.

Numeric sound effect IDs are liable to change between versions

Message ID	State	Bound To	Field Name	Field Type	Notes
0x67	Play	Client	Sound ID	VarInt	Represents the Sound ID + 1. If the value is 0, the message contains a sound specified by Identifier.
			Sound Name	Optional Identifier	Only present if Sound ID is 0
			Has Fixed Range	Optional Boolean	Only present if Sound ID is 0.
			Range	Optional Float	The fixed range of the sound. Only present if previous boolean is true and Sound ID is 0.
			Sound Category	VarInt Enum	The category that this sound will be played from (current categories).
			Entity ID	VarInt
			Volume	Float	1.0 is 100%, capped between 0.0 and 1.0 by Notchian clients.
			Pitch	Float	Float between 0.5 and 2.0 by Notchian clients.
			Seed	Long	Seed used to pick sound variant.

Sound Effect

Plays a sound effect at the given location, either by hardcoded ID or Identifier. Sound IDs and names can be found here.

Numeric sound effect IDs are liable to change between versions

Message ID	State	Bound To	Field Name	Field Type	Notes
0x68	Play	Client	Sound ID	VarInt	Represents the Sound ID + 1. If the value is 0, the message contains a sound specified by Identifier.
			Sound Name	Optional Identifier	Only present if Sound ID is 0
			Has Fixed Range	Optional Boolean	Only present if Sound ID is 0.
			Range	Optional Float	The fixed range of the sound. Only present if previous boolean is true and Sound ID is 0.
			Sound Category	VarInt Enum	The category that this sound will be played from (current categories).
			Effect Position X	Int	Effect X multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
			Effect Position Y	Int	Effect Y multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
			Effect Position Z	Int	Effect Z multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
			Volume	Float	1.0 is 100%, capped between 0.0 and 1.0 by Notchian clients.
			Pitch	Float	Float between 0.5 and 2.0 by Notchian clients.
			Seed	Long	Seed used to pick sound variant.

Start Configuration

Sent during gameplay in order to redo the configuration process. The client must respond with Acknowledge Configuration for the process to start.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x69	Play	Client	no fields

This message switches the connection state to configuration.

Stop Sound

Message ID	State	Bound To	Field Name	Field Type	Notes
0x6A	Play	Client	Flags	Byte	Controls which fields are present.
			Source	Optional VarInt Enum	Only if flags is 3 or 1 (bit mask 0x1). See below. If not present, then sounds from all sources are cleared.
			Sound	Optional Identifier	Only if flags is 2 or 3 (bit mask 0x2). A sound effect name, see Custom Sound Effect. If not present, then all sounds are cleared.

Categories:

Name	Value
master	0
music	1
record	2
weather	3
block	4
hostile	5
neutral	6
player	7
ambient	8
voice	9

Store Cookie (play)

Stores some arbitrary data on the client, which persists between server transfers. The Notchian client only accepts cookies of up to 5 kiB in size.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x6B	Play	Client	Key		Identifier		The identifier of the cookie.
			Payload Length		VarInt		Length of the following byte array.
			Payload		Byte Array (5120)		The data of the cookie.

System Chat Message

Main article: Chat

Sends the client a raw system message.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x6C	Play	Client	Content	Text Component	Limited to 262144 bytes.
			Overlay	Boolean	Whether the message is an actionbar or chat message. See also #Set Action Bar Text.

Set Tab List Header And Footer

This message may be used by custom servers to display additional information above/below the player list. It is never sent by the Notchian server.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x6D	Play	Client	Header	Text Component	To remove the header, send a empty text component: {"text":""}.
			Footer	Text Component	To remove the footer, send a empty text component: {"text":""}.

Tag Query Response

Sent in response to Query Block Entity Tag or Query Entity Tag.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x6E	Play	Client	Transaction ID	VarInt	Can be compared to the one sent in the original query message.
			NBT	NBT	The NBT of the block or entity. May be a TAG_END (0) in which case no NBT is present.

Pickup Item

Sent by the server when someone picks up an item lying on the ground — its sole purpose appears to be the animation of the item flying towards you. It doesn't destroy the entity in the client memory, and it doesn't add it to your inventory. The server only checks for items to be picked up after each Set Player Position (and Set Player Position And Rotation) message sent by the client. The collector entity can be any entity; it does not have to be a player. The collected entity also can be any entity, but the Notchian server only uses this for items, experience orbs, and the different varieties of arrows.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x6F	Play	Client	Collected Entity ID	VarInt
			Collector Entity ID	VarInt
			Pickup Item Count	VarInt	Seems to be 1 for XP orbs, otherwise the number of items in the stack.

Teleport Entity

This message is sent by the server when an entity moves more than 8 blocks.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x70	Play	Client	Entity ID	VarInt
			X	Double
			Y	Double
			Z	Double
			Yaw	Angle	(Y Rot)New angle, not a delta.
			Pitch	Angle	(X Rot)New angle, not a delta.
			On Ground	Boolean

Set Ticking State

Used to adjust the ticking rate of the client, and whether it's frozen.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x71	Play	Client	Tick rate	Float
			Is frozen	Boolean

Step Tick

Advances the client processing by the specified number of ticks. Has no effect unless client ticking is frozen.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x72	Play	Client	Tick steps	VarInt

Transfer (play)

Notifies the client that it should transfer to the given server. Cookies previously stored are preserved between server transfers.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x73	Play	Client	Host		String		The hostname of IP of the server.
			Port		VarInt		The port of the server.

Update Advancements

Message ID	State	Bound To	Field Name		Field Type		Notes
0x74	Play	Client	Reset/Clear		Boolean		Whether to reset/clear the current advancements.
			Mapping size		VarInt		Size of the following array.
			Advancement mapping	Key	Array	Identifier	The identifier of the advancement.
				Value		Advancement	See below
			List size		VarInt		Size of the following array.
			Identifiers		Array of Identifier		The identifiers of the advancements that should be removed.
			Progress size		VarInt		Size of the following array.
			Progress mapping	Key	Array	Identifier	The identifier of the advancement.
				Value		Advancement progress	See below.

Advancement structure:

Field Name		Field Type		Notes
Has parent		Boolean		Indicates whether the next field exists.
Parent id		Optional Identifier		The identifier of the parent advancement.
Has display		Boolean		Indicates whether the next field exists.
Display data		Optional Advancement display		See below.
Array length		VarInt		Number of arrays in the following array.
Requirements	Array length 2	Array	VarInt	Number of elements in the following array.
	Requirement		Array of String (32767)	Array of required criteria.
Sends telemetry data		Boolean		Whether the client should include this achievement in the telemetry data when it's completed. The Notchian client only sends data for advancements on the minecraft namespace.

Advancement display:

Field Name	Field Type	Notes
Title	Text Component
Description	Text Component
Icon	Slot
Frame type	VarInt Enum	0 = task, 1 = challenge, 2 = goal.
Flags	Int	0x01: has background texture; 0x02: show_toast; 0x04: hidden.
Background texture	Optional Identifier	Background texture location. Only if flags indicates it.
X coord	Float
Y coord	Float

Advancement progress:

Field Name		Field Type		Notes
Size		VarInt		Size of the following array.
Criteria	Criterion identifier	Array	Identifier	The identifier of the criterion.
	Criterion progress		Criterion progress

Criterion progress:

Field Name	Field Type	Notes
Achieved	Boolean	If true, next field is present.
Date of achieving	Optional Long	As returned by Date.getTime.

Update Attributes

Sets attributes on the given entity.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x75	Play	Client	Entity ID		VarInt
			Number Of Properties		VarInt		Number of elements in the following array.
			Property	Id	Array	VarInt Enum	See below.
				Value		Double	See below.
				Number Of Modifiers		VarInt	Number of elements in the following array.
				Modifiers		Array of Modifier Data	See Attribute#Modifiers. Modifier Data defined below.

Known Id values (see also Attribute#Modifiers):

Id	Key	Default	Min	Max	Label
0	generic.armor	0.0	0.0	30.0	Armor.
1	generic.armor_toughness	0.0	0.0	20.0	Armor Toughness.
2	generic.attack_damage	2.0	0.0	2048.0	Attack Damage.
3	generic.attack_knockback	0.0	0.0	5.0	Attack Knockback.
4	generic.attack_speed	4.0	0.0	1024.0	Attack Speed.
5	generic.block_break_speed	1.0	0.0	1024.0	Block Break Speed.
6	generic.block_interaction_range	4.5	0.0	64.0	Block Interaction Range.
7	generic.entity_interaction_range	3.0	0.0	64.0	Entity Interaction Range.
8	generic.fall_damage_multiplier	1.0	0.0	100.0	Fall Damage Multiplier.
9	generic.flying_speed	0.4	0.0	1024.0	Flying Speed.
10	generic.follow_range	32.0	0.0	2048.0	Follow Range.
11	generic.gravity	0.08	-1.0	1.0	Gravity.
12	generic.jump_strength	0.42	0.0	32.0	Jump Strength.
13	generic.knockback_resistance	0.0	0.0	1.0	Knockback Resistance.
14	generic.luck	0.0	-1024.0	1024.0	Luck.
15	generic.max_absorption	0.0	0.0	2048.0	Max Absorption.
16	generic.max_health	20.0	1.0	1024.0	Max Health.
17	generic.movement_speed	0.7	0.0	1024.0	Movement Speed.
18	generic.safe_fall_distance	3.0	-1024.0	1024.0	Safe Fall Distance.
19	generic.scale	1.0	0.0625	16.0	Scale.
20	zombie.spawn_reinforcements	0.0	0.0	1.0	Spawn Reinforcements Chance.
21	generic.step_height	0.6	0.0	10.0	Step Height.
22	generic.submerged_mining_speed	0.2	0.0	20.0	Submerged Mining Speed.
23	generic.sweeping_damage_ratio	0.0	0.0	1.0	Sweeping Damage Ratio.
24	generic.water_movement_efficiency	0.0	0.0	1.0	Water Movement Efficiency.

Modifier Data structure:

Field Name	Field Type	Notes
Id	Identifier
Amount	Double	May be positive or negative.
Operation	Byte	See below.

The operation controls how the base value of the modifier is changed.

• 0: Add/subtract amount
• 1: Add/subtract amount percent of the current value
• 2: Multiply by amount percent

All of the 0's are applied first, and then the 1's, and then the 2's.

Entity Effect

Message ID	State	Bound To	Field Name	Field Type	Notes
0x76	Play	Client	Entity ID	VarInt
			Effect ID	VarInt	See this table.
			Amplifier	VarInt	Notchian client displays effect level as Amplifier + 1.
			Duration	VarInt	Duration in ticks. (-1 for infinite)
			Flags	Byte	Bit field, see below.

	The following information needs to be added to this page:
	What exact effect does the blend bit flag have on the client? What happens if it is used on effects besides DARKNESS?

Within flags:

• 0x01: Is ambient - was the effect spawned from a beacon? All beacon-generated effects are ambient. Ambient effects use a different icon in the HUD (blue border rather than gray). If all effects on an entity are ambient, the "Is potion effect ambient" living metadata field should be set to true. Usually should not be enabled.
• 0x02: Show particles - should all particles from this effect be hidden? Effects with particles hidden are not included in the calculation of the effect color, and are not rendered on the HUD (but are still rendered within the inventory). Usually should be enabled.
• 0x04: Show icon - should the icon be displayed on the client? Usually should be enabled.
• 0x08: Blend - should the effect's hard-coded blending be applied? Currently only used in the DARKNESS effect to apply extra void fog and adjust the gamma value for lighting.

Update Recipes

Message ID	State	Bound To	Field Name		Field Type		Notes
0x77	Play	Client	Num Recipes		VarInt		Number of elements in the following array.
			Recipe	Recipe ID	Array	Identifier
				Type ID		VarInt Enum	The recipe type, see below.
				Data		Varies	Additional data for the recipe.

Recipe types:

ID	Type	Description	Data
0	minecraft:crafting_shaped	Shaped crafting recipe. All items must be present in the same pattern (which may be flipped horizontally or translated).	As follows: Name Type Description Group String (32767) Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Category VarInt Enum Building = 0, Redstone = 1, Equipment = 2, Misc = 3 Width VarInt Height VarInt Ingredients Array of Ingredient Length is width * height. Indexed by x + (y * width). Result Slot Show notification Boolean Show a toast when the recipe is added.
1	minecraft:crafting_shapeless	Shapeless crafting recipe. All items in the ingredient list must be present, but in any order/slot.	As follows: Name Type Description Group String (32767) Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Category VarInt Enum Building = 0, Redstone = 1, Equipment = 2, Misc = 3 Ingredient count VarInt Number of elements in the following array. Ingredients Array of Ingredient. Result Slot
2	minecraft:crafting_special_armordye	Recipe for dying leather armor	As follows: Name Type Description Category VarInt Enum Building = 0, Redstone = 1, Equipment = 2, Misc = 3
3	minecraft:crafting_special_bookcloning	Recipe for copying contents of written books
4	minecraft:crafting_special_mapcloning	Recipe for copying maps
5	minecraft:crafting_special_mapextending	Recipe for adding paper to maps
6	minecraft:crafting_special_firework_rocket	Recipe for making firework rockets
7	minecraft:crafting_special_firework_star	Recipe for making firework stars
8	minecraft:crafting_special_firework_star_fade	Recipe for making firework stars fade between multiple colors
9	minecraft:crafting_special_tippedarrow	Recipe for crafting tipped arrows
10	minecraft:crafting_special_bannerduplicate	Recipe for copying banner patterns
11	minecraft:crafting_special_shielddecoration	Recipe for applying a banner's pattern to a shield
12	minecraft:crafting_special_shulkerboxcoloring	Recipe for recoloring a shulker box
13	minecraft:crafting_special_suspiciousstew	Recipe for crafting suspicious stews
14	minecraft:crafting_special_repairitem	Recipe for repairing items via crafting
22	minecraft:crafting_decorated_pot	Recipe for crafting decorated pots
15	minecraft:smelting	Smelting recipe	As follows: Name Type Description Group String (32767) Used to group similar recipes together in the recipe book. Category VarInt Enum Food = 0, Blocks = 1, Misc = 2 Ingredient Ingredient Result Slot Experience Float Cooking time VarInt
16	minecraft:blasting	Blast furnace recipe
17	minecraft:smoking	Smoker recipe
18	minecraft:campfire_cooking	Campfire recipe
19	minecraft:stonecutting	Stonecutter recipe	As follows: Name Type Description Group String (32767) Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Ingredient Ingredient Result Slot
20	minecraft:smithing_transform	Recipe for smithing netherite gear	As follows: Name Type Description Template Ingredient The smithing template. Base Ingredient The base item. Addition Ingredient The additional ingredient. Result Slot
21	minecraft:smithing_trim	Recipe for applying armor trims	As follows: Name Type Description Template Ingredient The smithing template. Base Ingredient The base item. Addition Ingredient The additional ingredient.

Ingredient is defined as:

Name	Type	Description
Count	VarInt	Number of elements in the following array.
Items	Array of Slot	Any item in this array may be used for the recipe. The count of each item should be 1.

Update Tags (play)

Message ID	State	Bound To	Field Name		Field Type		Notes
0x78	Play	Client	Length of the array		VarInt
			Array of tags	Registry	Array	Identifier	Registry identifier (Vanilla expects tags for the registries minecraft:block, minecraft:item, minecraft:fluid, minecraft:entity_type, and minecraft:game_event)
				Array of Tag		(See below)

Tag arrays look like:

Field Name		Field Type		Notes
Length		VarInt		Number of elements in the following array
Tags	Tag name	Array	Identifier
	Count		VarInt	Number of elements in the following array
	Entries		Array of VarInt	Numeric IDs of the given type (block, item, etc.). This list replaces the previous list of IDs for the given tag. If some preexisting tags are left unmentioned, a warning is printed.

See Tag on the Minecraft Wiki for more information, including a list of vanilla tags.

Projectile Power

Message ID	State	Bound To	Field Name	Field Type	Notes
0x79	Play	Client	Entity ID	VarInt
			Power	Double

Custom Report Details

Contains a list of key-value text entries that are included in any crash or disconnection report generated during connection to the server.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x7A	Play	Client	Details Count		VarInt (32)		The number of details in the following array.
			Details	Title	Array	String (128)
				Description		String (4096)

Server Links

This message contains a list of links that the Notchian client will display in the menu available from the pause menu. Link labels can be built-in or custom (i.e., any text).

Message ID	State	Bound To	Field Name		Field Type		Notes
0x7B	Play	Client	Links Count		VarInt		The number of links in the following array.
			Links	Is built-in	Array	Boolean	Determines if the following label is built-in (from enum) or custom (text component).
				Label		VarInt Enum / Text Component	See below.
				URL		String	Valid URL.

ID	Name	Notes
0	Bug Report	Displayed on connection error screen; included as a comment in the disconnection report.
1	Community Guidelines
2	Support
3	Status
4	Feedback
5	Community
6	Website
7	Forums
8	News
9	Announcements

Serverbound

Confirm Teleportation

Sent by client as confirmation of Synchronize Player Position.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x00	Play	Server	Teleport ID	VarInt	The ID given by the Synchronize Player Position message.

Query Block Entity Tag

Used when F3+I is pressed while looking at a block.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x01	Play	Server	Transaction ID	VarInt	An incremental ID so that the client can verify that the response matches.
			Location	Position	The location of the block to check.

Change Difficulty

Must have at least op level 2 to use. Appears to only be used on singleplayer; the difficulty buttons are still disabled in multiplayer.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x02	Play	Server	New difficulty	Byte	0: peaceful, 1: easy, 2: normal, 3: hard .

Acknowledge Message

Message ID	State	Bound To	Field Name	Field Type	Notes
0x03	Play	Server	Message Count	VarInt

Chat Command

Main article: Chat

Message ID	State	Bound To	Field Name		Field Type		Notes
0x04	Play	Server	Command		String (32767)		The command typed by the client.

Signed Chat Command

Main article: Chat

Message ID	State	Bound To	Field Name		Field Type		Notes
0x05	Play	Server	Command		String (32767)		The command typed by the client.
			Timestamp		Long		The timestamp that the command was executed.
			Salt		Long		The salt for the following argument signatures.
			Array length		VarInt		Number of entries in the following array. The maximum length in Notchian server is 8.
			Array of argument signatures	Argument name	Array (8)	String (16)	The name of the argument that is signed by the following signature.
				Signature		Byte Array (256)	The signature that verifies the argument. Always 256 bytes and is not length-prefixed.
			Message Count		VarInt
			Acknowledged		Fixed BitSet (20)

Chat Message

Main article: Chat

Used to send a chat message to the server. The message may not be longer than 256 characters or else the server will kick the client.

The server will broadcast a Player Chat Message message with Chat Type minecraft:chat to all players that haven't disabled chat (including the player that sent the message). See Chat#Processing chat for more information.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x06	Play	Server	Message	String (256)
			Timestamp	Long
			Salt	Long	The salt used to verify the signature hash.
			Has Signature	Boolean	Whether the next field is present.
			Signature	Optional Byte Array (256)	The signature used to verify the chat message's authentication. When present, always 256 bytes and not length-prefixed.
			Message Count	VarInt
			Acknowledged	Fixed BitSet (20)

Player Session

Message ID	State	Bound To	Field Name		Field Type	Notes
0x07	Play	Server	Session Id		UUID
			Public Key	Expires At	Long	The time the play session key expires in epoch milliseconds.
				Public Key Length	VarInt	Length of the proceeding public key. Maximum length in Notchian server is 512 bytes.
				Public Key	Byte Array (512)	A byte array of an X.509-encoded public key.
				Key Signature Length	VarInt	Length of the proceeding key signature array. Maximum length in Notchian server is 4096 bytes.
				Key Signature	Byte Array (4096)	The signature consists of the player UUID, the key expiration timestamp, and the public key data. These values are hashed using SHA-1 and signed using Mojang's private RSA key.

Chunk Batch Received

Notifies the server that the chunk batch has been received by the client. The server uses the value sent in this message to adjust the number of chunks to be sent in a batch.

The Notchian server will stop sending further chunk data until the client acknowledges the sent chunk batch. After the first acknowledgement, the server adjusts this number to allow up to 10 unacknowledged batches.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x08	Play	Server	Chunks per tick	Float	Desired chunks per tick.

Client Status

Message ID	State	Bound To	Field Name	Field Type	Notes
0x09	Play	Server	Action ID	VarInt Enum	See below

Action ID values:

Action ID	Action	Notes
0	Perform respawn	Sent when the client is ready to complete login and when the client is ready to respawn after death.
1	Request stats	Sent when the client opens the Statistics menu.

Client Information (play)

Sent when the player connects, or when settings are changed.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0A	Play	Server	Locale	String (16)	e.g. en_GB.
			View Distance	Byte	Client-side render distance, in chunks.
			Chat Mode	VarInt Enum	0: enabled, 1: commands only, 2: hidden. See Chat#Client chat mode for more information.
			Chat Colors	Boolean	“Colors” multiplayer setting. Can the chat be colored?
			Displayed Skin Parts	Unsigned Byte	Bit mask, see below.
			Main Hand	VarInt Enum	0: Left, 1: Right.
			Enable text filtering	Boolean	Enables filtering of text on signs and written book titles. Currently always false (i.e. the filtering is disabled)
			Allow server listings	Boolean	Servers usually list online players, this option should let you not show up in that list.

Displayed Skin Parts flags:

• Bit 0 (0x01): Cape enabled
• Bit 1 (0x02): Jacket enabled
• Bit 2 (0x04): Left Sleeve enabled
• Bit 3 (0x08): Right Sleeve enabled
• Bit 4 (0x10): Left Pants Leg enabled
• Bit 5 (0x20): Right Pants Leg enabled
• Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Command Suggestions Request

Sent when the client needs to tab-complete a minecraft:ask_server suggestion type.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0B	Play	Server	Transaction Id	VarInt	The id of the transaction that the server will send back to the client in the response of this message. Client generates this and increments it each time it sends another tab completion that doesn't get a response.
			Text	String (32500)	All text behind the cursor without the / (e.g. to the left of the cursor in left-to-right languages like English).

Acknowledge Configuration

Sent by the client upon receiving a Start Configuration message from the server.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0C	Play	Server	no fields

This message switches the connection state to configuration.

Click Container Button

Used when clicking on window buttons. Until 1.14, this was only used by enchantment tables.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0D	Play	Server	Window ID	Byte	The ID of the window sent by Open Screen.
			Button ID	Byte	Meaning depends on window type; see below.

Window type	ID	Meaning
Enchantment Table	0	Topmost enchantment.
	1	Middle enchantment.
	2	Bottom enchantment.
Lectern	1	Previous page (which does give a redstone output).
	2	Next page.
	3	Take Book.
	100+page	Opened page number - 100 + number.
Stonecutter	Recipe button number - 4*row + col. Depends on the item.
Loom	Recipe button number - 4*row + col. Depends on the item.

Click Container

This message is sent by the client when the player clicks on a slot in a window.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x0E	Play	Server	Window ID		Unsigned Byte		The ID of the window which was clicked. 0 for player inventory. The server ignores any messages targeting a Window ID other than the current one, including ignoring 0 when any other window is open.
			State ID		VarInt		The last received State ID from either a Set Container Slot or a Set Container Content message.
			Slot		Short		The clicked slot number, see below.
			Button		Byte		The button used in the click, see below.
			Mode		VarInt Enum		Inventory operation mode, see below.
			Length of the array		VarInt		Maximum value for Notchian server is 128 slots.
			Array of changed slots	Slot number	Array (128)	Short
				Slot data		Slot	New data for this slot, in the client's opinion; see below.
			Carried item		Slot		Item carried by the cursor. Has to be empty (item ID = -1) for drop mode, otherwise nothing will happen.

See Inventory for further information about how slots are indexed.

After performing the action, the server compares the results to the slot change information included in the message, as applied on top of the server's view of the container's state prior to the action. For any slots that do not match, it sends Set Container Slot messages containing the correct results. If State ID does not match the last ID sent by the server, it will instead send a full Set Container Content to resynchronize the client.

When right-clicking on a stack of items, half the stack will be picked up and half left in the slot. If the stack is an odd number, the half left in the slot will be smaller of the amounts.

The distinct type of click performed by the client is determined by the combination of the Mode and Button fields.

Mode	Button	Slot	Trigger
0	0	Normal	Left mouse click
	1	Normal	Right mouse click
	0	-999	Left click outside inventory (drop cursor stack)
	1	-999	Right click outside inventory (drop cursor single item)
1	0	Normal	Shift + left mouse click
	1	Normal	Shift + right mouse click (identical behavior)
2	0	Normal	Number key 1
	1	Normal	Number key 2
	2	Normal	Number key 3
	⋮	⋮	⋮
	8	Normal	Number key 9
	⋮	⋮	Button is used as the slot index (impossible in vanilla clients)
	40	Normal	Offhand swap key F
3	2	Normal	Middle click, only defined for creative players in non-player inventories.
4	0	Normal*	Drop key (Q) (* Clicked item is always empty)
	1	Normal*	Control + Drop key (Q) (* Clicked item is always empty)
5	0	-999	Starting left mouse drag
	4	-999	Starting right mouse drag
	8	-999	Starting middle mouse drag, only defined for creative players in non-player inventories.
	1	Normal	Add slot for left-mouse drag
	5	Normal	Add slot for right-mouse drag
	9	Normal	Add slot for middle-mouse drag, only defined for creative players in non-player inventories.
	2	-999	Ending left mouse drag
	6	-999	Ending right mouse drag
	10	-999	Ending middle mouse drag, only defined for creative players in non-player inventories.
6	0	Normal	Double click
	1	Normal	Pickup all but check items in reverse order (impossible in vanilla clients)

Starting from version 1.5, “painting mode” is available for use in inventory windows. It is done by picking up stack of something (more than 1 item), then holding mouse button (left, right or middle) and dragging held stack over empty (or same type in case of right button) slots. In that case client sends the following to server after mouse button release (omitting first pickup message which is sent as usual):

1. message with mode 5, slot -999, button (0 for left | 4 for right);
2. message for every slot painted on, mode is still 5, button (1 | 5);
3. message with mode 5, slot -999, button (2 | 6);

If any of the painting messages other than the “progress” ones are sent out of order (for example, a start, some slots, then another start; or a left-click in the middle) the painting status will be reset.

Close Container

This message is sent by the client when closing a window.

Notchian clients send a Close Window message with Window ID 0 to close their inventory even though there is never an Open Screen message for the inventory.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x0F	Play	Server	Window ID	Unsigned Byte	This is the ID of the window that was closed. 0 for player inventory.

Change Container Slot State

This message is sent by the client when toggling the state of a Crafter.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x10	Play	Server	Slot ID	VarInt	This is the ID of the slot that was changed.
			Window ID	VarInt	This is the ID of the window that was changed.
			State	Boolean	The new state of the slot. True for enabled, false for disabled.

Cookie Response (play)

Response to a Cookie Request (play) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Message ID	State	Bound To	Field Name		Field Type		Notes
0x11	Play	Server	Key		Identifier		The identifier of the cookie.
			Has Payload		Boolean		The payload is only present if the cookie exists on the client.
			Payload Length		Optional VarInt		Length of the following byte array.
			Payload		Optional Byte Array (5120)		The data of the cookie, if any.

Serverbound Plugin Message (play)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses some plugin channels. These internal channels are in the minecraft namespace.

More documentation on this: https://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Note that the length of Data is known only from the message length, since the message has no length field of any kind.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x12	Play	Server	Channel	Identifier	Name of the plugin channel used to send the data.
			Data	Byte Array (32767)	Any data, depending on the channel. minecraft: channels are documented here. The length of this array must be inferred from the message length.

In Notchian server, the maximum data length is 32767 bytes.

Debug Sample Subscription

Subscribes to the specified type of debug sample data, which is then sent periodically to the client via Debug Sample.

The Notchian server only allows subscriptions from players that are server operators.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x13	Play	Server	Sample Type	VarInt Enum	The type of debug sample to subscribe to. Can be one of the following: 0 - Tick time

Edit Book

Message ID	State	Bound To	Field Name	Field Type	Notes
0x14	Play	Server	Slot	VarInt	The hotbar slot where the written book is located
			Count	VarInt	Number of elements in the following array. Maximum array size is 200.
			Entries	Array (200) of String (8192)	Text from each page. Maximum string length is 8192 chars.
			Has title	Boolean	If true, the next field is present. true if book is being signed, false if book is being edited.
			Title	Optional String (128)	Title of book.

Query Entity Tag

Used when F3+I is pressed while looking at an entity.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x15	Play	Server	Transaction ID	VarInt	An incremental ID so that the client can verify that the response matches.
			Entity ID	VarInt	The ID of the entity to query.

Interact

This message is sent from the client to the server when the client attacks or right-clicks another entity (a player, minecart, etc).

A Notchian server only accepts this message if the entity being attacked/used is visible without obstruction and within a 4-unit radius of the player's position.

The target X, Y, and Z fields represent the difference between the vector location of the cursor at the time of the message and the entity's position.

Note that middle-click in creative mode is interpreted by the client and sent as a Set Creative Mode Slot message instead.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x16	Play	Server	Entity ID	VarInt	The ID of the entity to interact. Note the special case described below.
			Type	VarInt Enum	0: interact, 1: attack, 2: interact at.
			Target X	Optional Float	Only if Type is interact at.
			Target Y	Optional Float	Only if Type is interact at.
			Target Z	Optional Float	Only if Type is interact at.
			Hand	Optional VarInt Enum	Only if Type is interact or interact at; 0: main hand, 1: off hand.
			Sneaking	Boolean	If the client is sneaking.

Interaction with the ender dragon is an odd special case characteristic of release deadline–driven design. 8 consecutive entity IDs following the dragon's ID (id + 1, id + 2, ..., id + 8) are reserved for the 8 hitboxes that make up the dragon:

ID offset	Description
0	The dragon itself (never used in this message)
1	Head
2	Neck
3	Body
4	Tail 1
5	Tail 2
6	Tail 3
7	Wing 1
8	Wing 2

Jigsaw Generate

Sent when Generate is pressed on the Jigsaw Block interface.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x17	Play	Server	Location	Position	Block entity location.
			Levels	VarInt	Value of the levels slider/max depth to generate.
			Keep Jigsaws	Boolean

Serverbound Keep Alive (play)

The server will frequently send out a keep-alive (see Clientbound Keep Alive), each containing a random ID. The client must respond with the same message.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x18	Play	Server	Keep Alive ID	Long

Lock Difficulty

Must have at least op level 2 to use. Appears to only be used on singleplayer; the difficulty buttons are still disabled in multiplayer.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x19	Play	Server	Locked	Boolean

Set Player Position

Updates the player's XYZ position on the server.

If the player is in a vehicle, the position is ignored (but in case of Set Player Position and Rotation, the rotation is still used as normal). No validation steps other than value range clamping are performed in this case.

If the player is sleeping, the position (or rotation) is not changed, and a Synchronize Player Position is sent if the received position deviated from the server's view by more than a meter.

The Notchian server silently clamps the x and z coordinates between -30,000,000 and 30,000,000, and the y coordinate between -20,000,000 and 20,000,000. A similar condition has historically caused a kick for "Illegal position"; this is no longer the case. However, infinite or NaN coordinates (or angles) still result in a kick for multiplayer.disconnect.invalid_player_movement.

As of 1.20.6, checking for moving too fast is achieved like this (sic):

• Each server tick, the player's current position is stored.
• When the player moves, the offset from the stored position to the requested position is computed (Δx, Δy, Δz).
• The requested movement distance squared is computed as Δx² + Δy² + Δz².
• The baseline expected movement distance squared is computed based on the player's server-side velocity as Vx² + Vy² + Vz². The player's server-side velocity is a somewhat ill-defined quantity that includes among other things gravity, jump velocity and knockback, but not regular horizontal movement. A proper description would bring much of Minecraft's physics engine with it. It is accessible as the Motion NBT tag on the player entity.
• The maximum permitted movement distance squared is computed as 100 (300 if the player is using an elytra), multiplied by the number of movement messages received since the last tick, including this one, unless that value is greater than 5, in which case no multiplier is applied.
• If the requested movement distance squared minus the baseline distance squared is more than the maximum squared, the player is moving too fast.

If the player is moving too fast, it is logged that "<player> moved too quickly! " followed by the change in x, y, and z, and the player is teleported back to their current (before this message) server-side position.

Checking for block collisions is achieved like this:

• A temporary collision-checked move of the player is attempted from its current position to the requested one.
• The offset from the resulting position to the requested position is computed. If the absolute value of the offset on the y axis is less than 0.5, it (only the y component) is rounded down to 0.
• If the magnitude of the offset is greater than 0.25 and the player isn't in creative or spectator mode, it is logged that "<player> moved wrongly!", and the player is teleported back to their current (before this message) server-side position.
• In addition, if the player's hitbox stationary at the requested position would intersect with a block, and they aren't in spectator mode, they are teleported back without a log message.

Checking for illegal flight is achieved like this:

• When a movement message is received, a flag indicating whether or not the player is floating mid-air is updated. The flag is set if the move test described above detected no collision below the player and the y component of the offset from the player's current position to the requested one is greater than -0.5, unless any of various conditions permitting flight (creative mode, elytra, levitation effect, etc., but not jumping) are met.
• Each server tick, it is checked if the flag has been set for more than 80 consecutive ticks. If so, and the player isn't currently sleeping, dead or riding a vehicle, they are kicked for multiplayer.disconnect.flying.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1A	Play	Server	X	Double	Absolute position.
			Feet Y	Double	Absolute feet position, normally Head Y - 1.62.
			Z	Double	Absolute position.
			On Ground	Boolean	True if the client is on the ground, false otherwise.

Set Player Position and Rotation

A combination of Move Player Rotation and Move Player Position.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1B	Play	Server	X	Double	Absolute position.
			Feet Y	Double	Absolute feet position, normally Head Y - 1.62.
			Z	Double	Absolute position.
			Yaw	Float	Absolute rotation on the X Axis, in degrees.
			Pitch	Float	Absolute rotation on the Y Axis, in degrees.
			On Ground	Boolean	True if the client is on the ground, false otherwise.

Set Player Rotation

The unit circle for yaw

The unit circle of yaw, redrawn

Updates the direction the player is looking in.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0,-1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw and pitch of player (in degrees), standing at point (x0, y0, z0) and looking towards point (x, y, z) can be calculated with:

dx = x-x0
dy = y-y0
dz = z-z0
r = sqrt( dx*dx + dy*dy + dz*dz )
yaw = -atan2(dx,dz)/PI*180
if yaw < 0 then
    yaw = 360 + yaw
pitch = -arcsin(dy/r)/PI*180

You can get a unit vector from a given yaw/pitch via:

x = -cos(pitch) * sin(yaw)
y = -sin(pitch)
z =  cos(pitch) * cos(yaw)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1C	Play	Server	Yaw	Float	Absolute rotation on the X Axis, in degrees.
			Pitch	Float	Absolute rotation on the Y Axis, in degrees.
			On Ground	Boolean	True if the client is on the ground, false otherwise.

Set Player On Ground

This message as well as Set Player Position, Set Player Rotation, and Set Player Position and Rotation are called the “serverbound movement messages”. Vanilla clients will send Move Player Position once every 20 ticks even for a stationary player.

This message is used to indicate whether the player is on ground (walking/swimming), or airborne (jumping/falling).

When dropping from sufficient height, fall damage is applied when this state goes from false to true. The amount of damage applied is based on the point where it last changed from true to false. Note that there are several movement related messages containing this state.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1D	Play	Server	On Ground	Boolean	True if the client is on the ground, false otherwise.

Move Vehicle

Sent when a player moves in a vehicle. Fields are the same as in Set Player Position and Rotation. Note that all fields use absolute positioning and do not allow for relative positioning.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1E	Play	Server	X	Double	Absolute position (X coordinate).
			Y	Double	Absolute position (Y coordinate).
			Z	Double	Absolute position (Z coordinate).
			Yaw	Float	Absolute rotation on the vertical axis, in degrees.
			Pitch	Float	Absolute rotation on the horizontal axis, in degrees.

Paddle Boat

Used to visually update whether boat paddles are turning. The server will update the Boat entity metadata to match the values here.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x1F	Play	Server	Left paddle turning	Boolean
			Right paddle turning	Boolean

Right paddle turning is set to true when the left button or forward button is held, left paddle turning is set to true when the right button or forward button is held.

Pick Item

Used to swap out an empty space on the hotbar with the item in the given inventory slot. The Notchian client uses this for pick block functionality (middle click) to retrieve items from the inventory.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Server	Slot to use	VarInt	See Inventory.

The server first searches the player's hotbar for an empty slot, starting from the current slot and looping around to the slot before it. If there are no empty slots, it starts a second search from the current slot and finds the first slot that does not contain an enchanted item. If there still are no slots that meet that criteria, then the server uses the currently selected slot.

After finding the appropriate slot, the server swaps the items and sends 3 messages:

• Set Container Slot with window ID set to -2, updating the chosen hotbar slot.
• Set Container Slot with window ID set to -2, updating the slot where the picked item used to be.
• Set Held Item, switching to the newly chosen slot.

Ping Request (play)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x21	Play	Server	Payload	Long	May be any number. Notchian clients use a system-dependent time value which is counted in milliseconds.

Place Recipe

This message is sent when a player clicks a recipe in the crafting book that is craftable (white border).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Server	Window ID	Byte
			Recipe	Identifier	A recipe ID.
			Make all	Boolean	Affects the amount of items processed; true if shift is down when clicked.

Player Abilities (serverbound)

The vanilla client sends this message when the player starts/stops flying with the Flags parameter changed accordingly.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x23	Play	Server	Flags	Byte	Bit mask. 0x02: is flying.

Player Action

Sent when the player mines a block. A Notchian server only accepts digging messages with coordinates within a 6-unit radius between the center of the block and the player's eyes.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x24	Play	Server	Status	VarInt Enum	The action the player is taking against the block (see below).
			Location	Position	Block position.
			Face	Byte Enum	The face being hit (see below).
			Sequence	VarInt	Block change sequence number (see #Acknowledge Block Change).

Status can be one of seven values:

Value	Meaning	Notes
0	Started digging	Sent when the player starts digging a block. If the block was instamined or the player is in creative mode, the client will not send Status = Finished digging, and will assume the server completed the destruction. To detect this, it is necessary to calculate the block destruction speed server-side.
1	Cancelled digging	Sent when the player lets go of the Mine Block key (default: left click). Face is always set to -Y.
2	Finished digging	Sent when the client thinks it is finished.
3	Drop item stack	Triggered by using the Drop Item key (default: Q) with the modifier to drop the entire selected stack (default: Control or Command, depending on OS). Location is always set to 0/0/0, Face is always set to -Y. Sequence is always set to 0.
4	Drop item	Triggered by using the Drop Item key (default: Q). Location is always set to 0/0/0, Face is always set to -Y. Sequence is always set to 0.
5	Shoot arrow / finish eating	Indicates that the currently held item should have its state updated such as eating food, pulling back bows, using buckets, etc. Location is always set to 0/0/0, Face is always set to -Y. Sequence is always set to 0.
6	Swap item in hand	Used to swap or assign an item to the second hand. Location is always set to 0/0/0, Face is always set to -Y. Sequence is always set to 0.

The Face field can be one of the following values, representing the face being hit:

Value	Offset	Face
0	-Y	Bottom
1	+Y	Top
2	-Z	North
3	+Z	South
4	-X	West
5	+X	East

Player Command

Sent by the client to indicate that it has performed certain actions: sneaking (crouching), sprinting, exiting a bed, jumping with a horse, and opening a horse's inventory while riding it.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x25	Play	Server	Entity ID	VarInt	Player ID
			Action ID	VarInt Enum	The ID of the action, see below.
			Jump Boost	VarInt	Only used by the “start jump with horse” action, in which case it ranges from 0 to 100. In all other cases it is 0.

Action ID can be one of the following values:

ID	Action
0	Start sneaking
1	Stop sneaking
2	Leave bed
3	Start sprinting
4	Stop sprinting
5	Start jump with horse
6	Stop jump with horse
7	Open vehicle inventory
8	Start flying with elytra

Leave bed is only sent when the “Leave Bed” button is clicked on the sleep GUI, not when waking up in the morning.

Open vehicle inventory is only sent when pressing the inventory key (default: E) while on a horse or chest boat — all other methods of opening such an inventory (involving right-clicking or shift-right-clicking it) do not use this message.

Player Input

Message ID	State	Bound To	Field Name	Field Type	Notes
0x26	Play	Server	Sideways	Float	Positive to the left of the player.
			Forward	Float	Positive forward.
			Flags	Unsigned Byte	Bit mask. 0x1: jump, 0x2: unmount.

Also known as 'Input' message.

Pong (play)

Response to the clientbound message (Ping) with the same id.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x27	Play	Server	ID	Int	id is the same as the ping message

Change Recipe Book Settings

Replaces Recipe Book Data, type 1.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x28	Play	Server	Book ID	VarInt Enum	0: crafting, 1: furnace, 2: blast furnace, 3: smoker.
			Book Open	Boolean
			Filter Active	Boolean

Set Seen Recipe

Sent when recipe is first seen in recipe book. Replaces Recipe Book Data, type 0.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x29	Play	Server	Recipe ID	Identifier

Rename Item

Sent as a player is renaming an item in an anvil (each keypress in the anvil UI sends a new Rename Item message). If the new name is empty, then the item loses its custom name (this is different from setting the custom name to the normal name of the item). The item name may be no longer than 50 characters long, and if it is longer than that, then the rename is silently ignored.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2A	Play	Server	Item name	String (32767)	The new name of the item.

Resource Pack Response (play)

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2B	Play	Server
			UUID	UUID	The unique identifier of the resource pack received in the Add Resource Pack (play) request.
			Result	VarInt Enum	Result ID (see below).

Result can be one of the following values:

ID	Result
0	Successfully downloaded
1	Declined
2	Failed to download
3	Accepted
4	Invalid URL
5	Failed to reload
6	Discarded

Seen Advancements

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2C	Play	Server	Action	VarInt Enum	0: Opened tab, 1: Closed screen.
			Tab ID	Optional Identifier	Only present if action is Opened tab.

Select Trade

When a player selects a specific trade offered by a villager NPC.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2D	Play	Server	Selected slot	VarInt	The selected slot in the players current (trading) inventory.

Set Beacon Effect

Changes the effect of the current beacon.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2E	Play	Server
			Has Primary Effect	Boolean
			Primary Effect	Optional VarInt	A Potion ID.
			Has Secondary Effect	Boolean
			Secondary Effect	Optional VarInt	A Potion ID.

Set Held Item (serverbound)

Sent when the player changes the slot selection.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x2F	Play	Server	Slot	Short	The slot which the player has selected (0–8).

Program Command Block

Message ID	State	Bound To	Field Name	Field Type	Notes
0x30	Play	Server
			Location	Position
			Command	String (32767)
			Mode	VarInt Enum	One of SEQUENCE (0), AUTO (1), or REDSTONE (2).
			Flags	Byte	0x01: Track Output (if false, the output of the previous command will not be stored within the command block); 0x02: Is conditional; 0x04: Automatic.

Program Command Block Minecart

Message ID	State	Bound To	Field Name	Field Type	Notes
0x31	Play	Server	Entity ID	VarInt
			Command	String (32767)
			Track Output	Boolean	If false, the output of the previous command will not be stored within the command block.

Set Creative Mode Slot

While the user is in the standard inventory (i.e., not a crafting bench) in Creative mode, the player will send this message.

Clicking in the creative inventory menu is quite different from non-creative inventory management. Picking up an item with the mouse actually deletes the item from the server, and placing an item into a slot or dropping it out of the inventory actually tells the server to create the item from scratch. (This can be verified by clicking an item that you don't mind deleting, then severing the connection to the server; the item will be nowhere to be found when you log back in.) As a result of this implementation strategy, the "Destroy Item" slot is just a client-side implementation detail that means "I don't intend to recreate this item.". Additionally, the long listings of items (by category, etc.) are a client-side interface for choosing which item to create. Picking up an item from such listings sends no messages to the server; only when you put it somewhere does it tell the server to create the item in that location.

This action can be described as "set inventory slot". Picking up an item sets the slot to item ID -1. Placing an item into an inventory slot sets the slot to the specified item. Dropping an item (by clicking outside the window) effectively sets slot -1 to the specified item, which causes the server to spawn the item entity, etc.. All other inventory slots are numbered the same as the non-creative inventory (including slots for the 2x2 crafting menu, even though they aren't visible in the vanilla client).

Message ID	State	Bound To	Field Name	Field Type	Notes
0x32	Play	Server	Slot	Short	Inventory slot.
			Clicked Item	Slot

Program Jigsaw Block

Sent when Done is pressed on the Jigsaw Block interface.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x33	Play	Server	Location	Position	Block entity location
			Name	Identifier
			Target	Identifier
			Pool	Identifier
			Final state	String (32767)	"Turns into" on the GUI, final_state in NBT.
			Joint type	String (32767)	rollable if the attached piece can be rotated, else aligned.
			Selection priority	VarInt
			Placement priority	VarInt

Program Structure Block

Message ID	State	Bound To	Field Name	Field Type	Notes
0x34	Play	Server
			Location	Position	Block entity location.
			Action	VarInt Enum	An additional action to perform beyond simply saving the given data; see below.
			Mode	VarInt Enum	One of SAVE (0), LOAD (1), CORNER (2), DATA (3).
			Name	String (32767)
			Offset X	Byte	Between -48 and 48.
			Offset Y	Byte	Between -48 and 48.
			Offset Z	Byte	Between -48 and 48.
			Size X	Byte	Between 0 and 48.
			Size Y	Byte	Between 0 and 48.
			Size Z	Byte	Between 0 and 48.
			Mirror	VarInt Enum	One of NONE (0), LEFT_RIGHT (1), FRONT_BACK (2).
			Rotation	VarInt Enum	One of NONE (0), CLOCKWISE_90 (1), CLOCKWISE_180 (2), COUNTERCLOCKWISE_90 (3).
			Metadata	String (128)
			Integrity	Float	Between 0 and 1.
			Seed	VarLong
			Flags	Byte	0x01: Ignore entities; 0x02: Show air; 0x04: Show bounding box.

Possible actions:

• 0 - Update data
• 1 - Save the structure
• 2 - Load the structure
• 3 - Detect size

The Notchian client uses update data to indicate no special action should be taken (i.e. the done button).

Update Sign

This message is sent from the client to the server when the “Done” button is pushed after placing a sign.

The server only accepts this message after Open Sign Editor, otherwise this message is silently ignored.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x35	Play	Server	Location	Position	Block Coordinates.
			Is Front Text	Boolean	Whether the updated text is in front or on the back of the sign
			Line 1	String (384)	First line of text in the sign.
			Line 2	String (384)	Second line of text in the sign.
			Line 3	String (384)	Third line of text in the sign.
			Line 4	String (384)	Fourth line of text in the sign.

Swing Arm

Sent when the player's arm swings.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x36	Play	Server	Hand	VarInt Enum	Hand used for the animation. 0: main hand, 1: off hand.

Teleport To Entity

Teleports the player to the given entity. The player must be in spectator mode.

The Notchian client only uses this to teleport to players, but it appears to accept any type of entity. The entity does not need to be in the same dimension as the player; if necessary, the player will be respawned in the right world. If the given entity cannot be found (or isn't loaded), this message will be ignored. It will also be ignored if the player attempts to teleport to themselves.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x37	Play	Server	Target Player	UUID	UUID of the player to teleport to (can also be an entity UUID).

Use Item On

Message ID	State	Bound To	Field Name	Field Type	Notes
0x38	Play	Server	Hand	VarInt Enum	The hand from which the block is placed; 0: main hand, 1: off hand.
			Location	Position	Block position.
			Face	VarInt Enum	The face on which the block is placed (as documented at Player Action).
			Cursor Position X	Float	The position of the crosshair on the block, from 0 to 1 increasing from west to east.
			Cursor Position Y	Float	The position of the crosshair on the block, from 0 to 1 increasing from bottom to top.
			Cursor Position Z	Float	The position of the crosshair on the block, from 0 to 1 increasing from north to south.
			Inside block	Boolean	True when the player's head is inside of a block.
			Sequence	VarInt	Block change sequence number (see #Acknowledge Block Change).

Upon placing a block, this message is sent once.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to sixteen pixels in the default resource pack. For example, let's say a slab is being placed against the south face of a full block. The Cursor Position X will be higher if the player was pointing near the right (east) edge of the face, lower if pointing near the left. The Cursor Position Y will be used to determine whether it will appear as a bottom slab (values 0.0–0.5) or as a top slab (values 0.5-1.0). The Cursor Position Z should be 1.0 since the player was looking at the southernmost part of the block.

Inside block is true when a player's head (specifically eyes) are inside of a block's collision. In 1.13 and later versions, collision is rather complicated and individual blocks can have multiple collision boxes. For instance, a ring of vines has a non-colliding hole in the middle. This value is only true when the player is directly in the box. In practice, though, this value is only used by scaffolding to place in front of the player when sneaking inside of it (other blocks will place behind when you intersect with them -- try with glass for instance).

Use Item

Sent when pressing the Use Item key (default: right click) with an item in hand.

Message ID	State	Bound To	Field Name	Field Type	Notes
0x39	Play	Server	Hand	VarInt Enum	Hand used for the animation. 0: main hand, 1: off hand.
			Sequence	VarInt	Block change sequence number (see #Acknowledge Block Change).
			Yaw	Float	Player head rotation along the Y-Axis.
			Pitch	Float	Player head rotation along the X-Axis.