Pre-release protocol
This page documents the changes from the last stable Minecraft release (currently 1.20.1, protocol 763) to the current pre-release (currently 23w31a, protocol Snapshot 144). Note that this page contains bleeding-edge information that may not be completely or correctly documented.
One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.
Contents
Data types
No changes so far.
Packets
Packets
ID | Packet name | Documentation | |
---|---|---|---|
Login clientbound | |||
0x02 | Login Success | Current | Pre |
Login serverbound | |||
0x00 | Login Start | Current | Pre |
0x03 | Login Acknowledged | Pre | |
Configuration clientbound | |||
0x00 | Plugin Message (configuration) | Pre | |
0x01 | Disconnect (configuration) | Pre | |
0x02 | Finish Configuration | Pre | |
0x03 | Keep Alive (configuration) | Pre | |
0x04 | Ping (configuration) | Pre | |
0x05 | Registry Data | Pre | |
0x06 | Resource Pack (configuration) | Pre | |
0x07 | Feature Flags | Pre | |
0x08 | Update Tags | Pre | |
Configuration serverbound | |||
0x00 | Plugin Message (configuration) | Pre | |
0x01 | Finish Configuration | Pre | |
0x02 | Keep Alive (configuration) | Pre | |
0x03 | Pong (configuration) | Pre | |
0x04 | Resource Pack | Pre | |
Play clientbound | |||
0x0D | Chunk Batch Finished | Pre | |
0x0E | Chunk Batch Start | Pre | |
Login (play) | Current | Pre | |
Respawn | Current | Pre | |
Display Objective | Current | Pre | |
0x65 | Start Configuration | Pre | |
0x68 | Feature Flags | Current | |
Play serverbound | |||
0x08 | Chunk Batch Received | Pre | |
0x0B | Configuration Acknowledged | Pre |
New/modified data types
No changes so far.
Entity Metadata
No changes so far.
Entity
No changes so far.
Block Actions
No changes so far.
Inventories
No changes so far.
Plugin Channels
No changes so far.
Play
Clientbound
Chunk Batch Finished
The following information needs to be added to this page: | |
Why does the formula uses 25 instead of the normal tick duration of 50 ?
|
Marks the end of a chunk batch. The Notchian client marks the time it receives this packet and calculates the ellapsed duration since the beggining of the chunk batch. The server uses this duration and the batch size received in this packet to estimate the number of milliseconds ellapsed 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.
The Notchian client uses the samples from the latest 15 batches to estimate the chunks per millisecond number.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x0D | 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 packet.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x0E | Play | Client | no fields |
Login (play)
See Protocol Encryption for information on logging in.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
Play | Client | Entity ID | Int | The player's Entity ID (EID). | |
Is hardcore | Boolean | ||||
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) | |||
Dimension Count | VarInt | Size of the following array. | |||
Dimension Names | Array of Identifier | Identifiers for all dimensions on the server. | |||
Registry Codec | NBT Tag Compound | Represents certain registries that are sent from the server and are applied on the client. | |||
Dimension Type | Identifier | Name of the dimension type being spawned into. | |||
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 | |||
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. | |||
Dimension Type | Identifier | Name of the dimension type being spawned into. | |||
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. |
Respawn
To change the player's dimension (overworld/nether/end), send them a respawn packet with the appropriate dimension, followed by prechunks/chunks for the new dimension, and finally a position and look packet. You do not need to unload chunks, the client will do it automatically.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
Play | Client | Dimension Type | Identifier | Valid dimensions are defined per dimension registry sent in Login (play) | |
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. | |||
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:
| |||
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. |
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 packets, 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 packets.
Display Objective
This is sent to the client when it should display a scoreboard.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
Play | Client | Position | 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 |
The unique name for the scoreboard to be displayed. |
Start Configuration
Sent during gameplay in order to redo the configuration process. The client must respond with Configuration Acknowledged for the process to start.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x65 | Play | Client | no fields |
This packet switches the connection state to configuration.
Feature Flags
Used to enable and disable features, generally experimental ones, on the client.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x6B | Play | Client | Total Features | VarInt | Number of features that appear in the array below. |
Feature Flags | Identifier Array |
Serverbound
Chunk Batch Received
Notifies the server that the chunk batch has been received by the client. The server uses the value sent in this packet to adjust the number of chunks to be sent in a batch.
The Notchian server will begin by stopping to send more chunk data until the client acknowledges one chunk batch. After the first acknowledgement, the number increases to 10 batches.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x07 | Play | Server | Chunks per tick | Float | Desired chunks per tick. |
Configuration Acknowledged
Sent by the client upon received a Start Configuration packet from the server.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x0B | Play | Server | no fields |
This packet switches the connection state to configuration.
Status
Clientbound
No changes so far.
Serverbound
No changes so far.
Login
Clientbound
Login Success
Packet 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. |
This packet switches the connection state to play configuration.
Serverbound
Login Start
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x00 | Login | Server | Name | String (16) | Player's Username. |
Has Player UUID | Boolean | Whether or not the next field should be sent. | |||
Player UUID | The UUID of the player logging in. |
Login Acknowledged
Acknowledgement to the Login Success packet sent by the server.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x03 | Login | Server | no fields |
Configuration
Clientbound
Plugin Message (configuration)
- Main article: Plugin channels
Mods and plugins can use this to send their data. Minecraft itself uses the minecraft:payload
channel to send many types of payloads, which are documented here.
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 packet length, since the packet has no length field of any kind.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x00 | Configuration | Client | Channel | Identifier | Name of the plugin channel used to send the data. |
Payload | Byte Array (1048576) | Any data, depending on the channel. minecraft:payload payloads are documented here. The length of this array must be inferred from the packet length.
|
In Notchian client, the maximum data length is 1048576 bytes.
Disconnect (configuration)
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x01 | Configuration | Client | Reason | Chat | The reason why the player was disconnected. |
Finish Configuration
Sent by the server to notify the client that all the configuration has finish. The client answers with its own Finish Configuration whenever it is ready to continue.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x02 | Configuration | Client | no fields |
This packet switches the connection state to play.
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 them for over 30 seconds, 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.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x03 | Configuration | Client | Keep Alive ID | Long |
Ping (configuration)
Packet is not used by the Notchian server. When sent to the client, client responds with a Pong packet with the same id.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x04 | Configuration | Client | ID | Int |
Registry Data
Represents certain registries that are sent from the server and are applied on the client.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x05 | Configuration | Client | Registry Codec | NBT Tag Compound | Information included below. |
The Registry Codec NBT Tag Compound (Default value in JSON as of 1.19, 1.19.2, 1.20.1) includes three registries: "minecraft:dimension_type", "minecraft:worldgen/biome", and "minecraft:chat_type".
Name | Type | Notes | |
---|---|---|---|
minecraft:dimension_type | TAG_Compound | The dimension type registry (see below). | |
minecraft:worldgen/biome | TAG_Compound | The biome registry (see below). | |
minecraft:chat_type | TAG_Compound | The chat type registry (see below). |
Dimension type registry:
Name | Type | Notes | |
---|---|---|---|
type | TAG_String | The name of the registry. Always "minecraft:dimension_type". | |
value | TAG_List | List of dimension types registry entries (see below). |
Dimension type registry entry:
Name | Type | Notes | |
---|---|---|---|
name | TAG_String | The name of the dimension type (for example, "minecraft:overworld"). | |
id | TAG_Int | The protocol ID of the dimension (matches the index of the element in the registry list). | |
element | TAG_Compound | The dimension type (see below). |
Dimension type:
Name | Type | Meaning | Values | |
---|---|---|---|---|
piglin_safe | TAG_Byte | Whether piglins shake and transform to zombified piglins. | 1: true, 0: false. | |
has_raids | TAG_Byte | Whether players with the Bad Omen effect can cause a raid. | 1: true, 0: false. | |
monster_spawn_light_level | TAG_Int or TAG_Compound | Possibly the light level(s) at which monsters can spawn. | When TAG_Int, 0 - 15. When TAG_Compound, contains the fields: type (TAG_String), appears to be always "minecraft:uniform", and value (TAG_Compound), which contains the fields: max_inclusive (TAG_Int), min_inclusive (TAG_Int). | |
monster_spawn_block_light_limit | TAG_Int | |||
natural | TAG_Byte | When false, compasses spin randomly. When true, nether portals can spawn zombified piglins. | 1: true, 0: false. | |
ambient_light | TAG_Float | How much light the dimension has. | 0.0 to 1.0. | |
fixed_time | Optional TAG_Long | If set, the time of the day is the specified value. | If set, 0 to 24000. | |
infiniburn | TAG_String | A resource location defining what block tag to use for infiniburn. | "#" or minecraft resource "#minecraft:...". | |
respawn_anchor_works | TAG_Byte | Whether players can charge and use respawn anchors. | 1: true, 0: false. | |
has_skylight | TAG_Byte | Whether the dimension has skylight access or not. | 1: true, 0: false. | |
bed_works | TAG_Byte | Whether players can use a bed to sleep. | 1: true, 0: false. | |
effects | TAG_String | ? | "minecraft:overworld", "minecraft:the_nether", "minecraft:the_end" or something else. | |
min_y | TAG_Int | The minimum Y level. | A multiple of 16. Example: -64 | |
height | TAG_Int | The maximum height. | A multiple of 16. Example: 256 | |
logical_height | TAG_Int | The maximum height to which chorus fruits and nether portals can bring players within this dimension. (Must be lower than height) | 0-384. | |
coordinate_scale | TAG_Double | The multiplier applied to coordinates when traveling to the dimension. | 0.00001 - 30000000.0 | |
ultrawarm | TAG_Byte | Whether the dimensions behaves like the nether (water evaporates and sponges dry) or not. Also causes lava to spread thinner. | 1: true, 0: false. | |
has_ceiling | TAG_Byte | Whether the dimension has a bedrock ceiling or not. When true, causes lava to spread faster. | 1: true, 0: false. |
Biome registry:
Name | Type | Notes | |
---|---|---|---|
type | TAG_String | The name of the registry. Always "minecraft:worldgen/biome". | |
value | TAG_List | List of biome registry entries (see below). |
Biome registry entry:
Name | Type | Notes | |
---|---|---|---|
name | TAG_String | The name of the biome (for example, "minecraft:ocean"). | |
id | TAG_Int | The protocol ID of the biome (matches the index of the element in the registry list). | |
element | TAG_Compound | The biome properties (see below). |
Biome properties:
Name | Type | Meaning | Values | |||||
---|---|---|---|---|---|---|---|---|
has_precipitation | TAG_Byte | Determines whether or not the biome has precipitation. | 1: true, 0: false. | |||||
depth | Optional TAG_Float | The depth factor of the biome. | The default values vary between 1.5 and -1.8. | |||||
temperature | TAG_Float | The temperature factor of the biome. | The default values vary between 2.0 and -0.5. | |||||
scale | Optional TAG_Float | ? | The default values vary between 1.225 and 0.0. | |||||
downfall | TAG_Float | ? | The default values vary between 1.0 and 0.0. | |||||
category | Optional TAG_String | The category of the biome. | Known values are "ocean", "plains", "desert", "forest", "extreme_hills", "taiga", "swamp", "river", "nether", "the_end", "icy", "mushroom", "beach", "jungle", "mesa", "savanna", and "none". | |||||
temperature_modifier | Optional TAG_String | ? | The only known value is "frozen". | |||||
effects | sky_color | TAG_Compound | TAG_Int | The color of the sky. | Example: 8364543, which is #7FA1FF in RGB. | |||
water_fog_color | TAG_Int | Possibly the tint color when swimming. | Example: 8364543, which is #7FA1FF in RGB. | |||||
fog_color | TAG_Int | Possibly the color of the fog effect when looking past the view distance. | Example: 8364543, which is #7FA1FF in RGB. | |||||
water_color | TAG_Int | The tint color of the water blocks. | Example: 8364543, which is #7FA1FF in RGB. | |||||
foliage_color | Optional TAG_Int | The tint color of the grass. | Example: 8364543, which is #7FA1FF in RGB. | |||||
grass_color | Optional TAG_Int | ? | Example: 8364543, which is #7FA1FF in RGB. | |||||
grass_color_modifier | Optional TAG_String | Unknown, likely affects foliage color. | If set, known values are "swamp" and "dark_forest". | |||||
music | Optional TAG_Compound | Music properties for the biome. | If present, contains the fields: replace_current_music (TAG_Byte), sound (TAG_String), max_delay (TAG_Int), min_delay (TAG_Int). | |||||
ambient_sound | Optional TAG_String | Ambient soundtrack. | If present, the ID of a soundtrack. Example: "minecraft:ambient.basalt_deltas.loop". | |||||
additions_sound | Optional TAG_Compound | Additional ambient sound that plays randomly. | If present, contains the fields: sound (TAG_String), tick_chance (TAG_Double). | |||||
mood_sound | Optional TAG_Compound | Additional ambient sound that plays at an interval. | If present, contains the fields: sound (TAG_String), tick_delay (TAG_Int), offset (TAG_Double), block_search_extent (TAG_Int). | |||||
particle | probability | Optional TAG_Compound | TAG_FLOAT | Particles that appear randomly in the biome. | Possibly the probability of spawning the particle. | ? | ||
options | TAG_COMPOUND | The properties of the particle to spawn. | Contains the field "type" (TAG_String), which identifies the particle type. |
Chat registry:
Name | Type | Notes | |
---|---|---|---|
type | TAG_String | The name of the registry. Always "minecraft:chat_type". | |
value | TAG_List | List of chat type registry entries (see below). |
Chat type:
Name | Type | Notes | |
---|---|---|---|
name | TAG_String | The type's name (eg "minecraft:chat") | |
id | TAG_Int | ||
elements | TAG_Compound | "chat" and "narration" TAG_Compound's (see below) |
Chat type "chat" and "narration":
Name | Type | Notes | |
---|---|---|---|
translation_key | TAG_String | ||
style | TAG_Compound | Similar to Chat JSON (only present in "chat" TAG_Compound) | |
parameters | TAG_List of TAG_String | Values can be "sender", "target" and "content" |
Resource Pack
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x06 | Configuration | Client | URL | String (32767) | The URL to the resource pack. |
Hash | String (40) | A 40 character hexadecimal and lowercase 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 — but it will still treat it as a unique id | |||
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 | true If the next field will be sent false otherwise. When false , this is the end of the packet
| |||
Prompt Message | Optional Chat | This is shown in the prompt making the client accept or decline the resource pack. |
Feature Flags
Used to enable and disable features, generally experimental ones, on the client.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x07 | Configuration | Client | Total Features | VarInt | Number of features that appear in the array below. |
Feature Flags | Identifier Array |
As of 23w31a, 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
Packet ID | State | Bound To | Field Name | Field Type | Notes | ||
---|---|---|---|---|---|---|---|
0x08 | Configuration | Client | Length of the array | VarInt | |||
Array of tags | Tag type | Array | Identifier | Tag identifier (Vanilla required tags are minecraft:block , minecraft:item , minecraft:fluid , minecraft:entity_type , and minecraft:game_event )
| |||
Array of Tag | (See below) |
Tags 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 ID of the given type (block, item, etc.). |
More information on tags is available at: https://minecraft.gamepedia.com/Tag
And a list of all tags is here: https://minecraft.gamepedia.com/Tag#List_of_tags
Serverbound
Plugin Message (configuration)
- Main article: Plugin channels
Mods and plugins can use this to send their data. Minecraft itself uses the minecraft:payload
channel to send many types of payloads, which are documented here.
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 packet length, since the packet has no length field of any kind.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x00 | Configuration | Server | Channel | Identifier | Name of the plugin channel used to send the data. |
Payload | Byte Array (32767) | Any data, depending on the channel. minecraft:payload payloads are documented here. The length of this array must be inferred from the packet length.
|
In Notchian server, the maximum data length is 32767 bytes.
Finish Configuration
Sent by the client to notify the client that all the configuration has finished. It is sent after the server sends its own Finish Configuration.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x01 | Configuration | Server | no fields |
This packet switches the connection state to play.
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 packet.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x02 | Configuration | Server | Keep Alive ID | Long |
Pong (configuration)
Response to the clientbound packet (Ping) with the same id.
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x03 | Configuration | Server | ID | Int | id is the same as the ping packet |
Resource Pack (configuration)
Packet ID | State | Bound To | Field Name | Field Type | Notes |
---|---|---|---|---|---|
0x04 | Configuration | Server | Result | VarInt Enum | 0: successfully loaded, 1: declined, 2: failed download, 3: accepted. |