Pre-release protocol

This page documents the changes from release 1.21.1 (protocol 767) to the current release (1.21.3, protocol 768). The stable protocol documentation is currently lagging behind, and the changes documented here will be merged soon, once they are complete. The current pre-release (snapshot 24w44a) is not yet 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

Name	Size (bytes)	Encodes	Notes
Teleport Flags	4	Bit field specifying how a teleportation is to be applied on each axis.	See #Teleport Flags
ID Set	Varies	Set of registry IDs specified either inline or as a reference to a tag.	See #ID Set

Teleport Flags

A bit field represented as an Int, specifying how a teleportation is to be applied on each axis.

In the lower 8 bits of the bit field, a set bit means the teleportation on the corresponding axis is relative, and an unset bit that it is absolute.

Hex Mask	Field
0x0001	Relative X
0x0002	Relative Y
0x0004	Relative Z
0x0008	Relative Yaw
0x0010	Relative Pitch
0x0020	Relative Velocity X
0x0040	Relative Velocity Y
0x0080	Relative Velocity Z
0x0100	Rotate velocity according to the change in rotation, before applying the velocity change in this packet. Combining this with absolute rotation works as expected—the difference in rotation is still used.

ID Set

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

Name	Type	Description
Type	VarInt	Identifier 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.

Packets

ID	Packet name	Documentation
Play clientbound
0x12	Close Container	Current	Pre
0x13	Set Container Content	Current	Pre
0x14	Set Container Property	Current	Pre
0x15	Set Container Slot	Current	Pre
0x17	Set Cooldown	Current	Pre
0x20	Synchronize Entity Position		Pre
0x20 0x21	Explosion	Current	Pre
0x23 0x24	Open Horse Screen	Current	Pre
0x2B 0x2C	Login (play)	Current	Pre
0x31	Move Minecart Along Track		Pre
0x37 0x39	Place Ghost Recipe	Current	Pre
0x3E 0x40	Player Info Update	Current	Pre
0x40 0x42	Synchronize Player Position	Current	Pre
0x41	Update Recipe Book	Current
0x43	Player Rotation		Pre
0x44	Recipe Book Add		Pre
0x45	Recipe Book Remove		Pre
0x46	Recipe Book Settings		Pre
0x47 0x4C	Respawn	Current	Pre
0x5a	Set Cursor Item		Pre
0x53 0x63	Set Held Item	Current	(unchanged)
0x66	Set Player Inventory Slot		Pre
0x64 0x6b	Update Time	Current	Pre
0x70 0x77	Teleport Entity	Current	Pre
Play serverbound
0x02	Bundle Item Selected		Pre
0x0b	Client Tick End		Pre
0x0E 0x10	Click Container	Current	Pre
0x0F 0x11	Close Container	Current	Pre
0x14 0x16	Edit Book	Current	Pre
0x1A 0x1C	Set Player Position	Current	Pre
0x1B 0x1D	Set Player Position and Rotation	Current	Pre
0x1C 0x1E	Set Player Rotation	Current	Pre
0x1D	Set Player On Ground	Current
0x1F	Set Player Movement Flags		Pre
0x22 0x24	Place Recipe	Current	Pre
0x26 0x28	Player Input	Current	Pre
0x29 0x2B	Set Seen Recipe	Current	Pre

Handshake

No changes so far.

Status

No changes so far.

Login

No changes so far.

Configuration

No changes so far.

Play

Clientbound

Close Container

This packet 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.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x12	Play	Client	Window ID	Unsigned Byte VarInt	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).

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x13	Play	Client	Window ID	Unsigned Byte VarInt	The ID of window which items are being sent for. 0 for player inventory. The client ignores any packets 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 packet is used to inform the client that part of a GUI window should be updated.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14	Play	Client	Window ID	Unsigned Byte VarInt
			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.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x15	Play	Client	Window ID	Unsigned Byte VarInt	The window which is being updated. 0 for player inventory. The client ignores any packets targeting a Window ID other than the current one; see below for exceptions , unless it is 0 (see below).
			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.

Set Cooldown

Applies a cooldown period to all items with the given type. Used by the Notchian server with enderpearls. This packet 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).

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

Synchronize Entity Position

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Entity ID	VarInt
			X	Double
			Y	Double
			Z	Double
			Velocity X	Double
			Velocity Y	Double
			Velocity Z	Double
			Yaw	Float	Rotation on the X axis, in degrees.
			Pitch	Float	Rotation on the Y axis, in degrees.
			On Ground	Boolean

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

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x20 0x21	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.
			Has Player Motion		Boolean
			Player Motion X		Float Optional Double	X velocity of the player being pushed by the explosion. Only present if Has Player Motion is true.
			Player Motion Y		Float Optional Double	Y velocity of the player being pushed by the explosion. Only present if Has Player Motion is true.
			Player Motion Z		Float Optional Double	Z velocity of the player being pushed by the explosion. Only present if Has Player Motion is true.
			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 ID	VarInt	Represents the Sound ID + 1. If the value is 0, the packet contains a sound specified by Identifier.
				Sound Name	Optional Identifier	The name of the sound played. Only present if Sound ID is 0.
				Has Fixed Range	Optional Boolean	Whether is has fixed range. 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.

Open Horse Screen

This packet 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.

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

Login (play)

	The following information needs to be added to this page:
	Although the number of portal cooldown ticks is included in this packet, 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.

Packet ID	State	Bound To	Field Name	Field Type	Notes
protocol: 0x2B 0x2C resource: login	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 packet.
			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.
			Sea level	VarInt
			Enforces Secure Chat	Boolean

Move Minecart Along Track

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x31	Play	Client	Entity ID		VarInt
			Step Count		VarInt		Number of elements in the following array.
			Steps	X	Array	Double
				Y		Double
				Z		Double
				Velocity X		Double
				Velocity Y		Double
				Velocity Z		Double
				Yaw		Angle
				Pitch		Angle
				Weight		Float

Player Info Update

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

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x3E 0x40	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.
Update List Priority	0x40	Priority		VarInt		See below.

The properties included in this packet 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.

The order of players in the player list is determined as follows:

• Players with higher priorities are sorted before those with lower priorities.
• Among players of equal priorities, spectators are sorted after non-spectators.
• Within each of those groups, players are sorted into teams. The teams are ordered case-sensitively by team name in ascending order. Players with no team are listed first.
• The players of each team (and non-team) are sorted case-insensitively by name in ascending order.

Synchronize Player Position

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

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

Packet ID	State	Bound To	Field Name	Field Type	Notes
protocol: 0x40 0x42 resource: player_position	Play	Client	Teleport ID	VarInt	Client should confirm this packet with Confirm Teleportation containing the same Teleport ID.
			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.
			Velocity X	Double
			Velocity Y	Double
			Velocity Z	Double
			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 Teleport Flags	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 packet with Confirm Teleportation containing the same Teleport ID.

Player Rotation

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x43	Play	Client	Yaw	Float	Rotation on the X axis, in degrees.
			Pitch	Float	Rotation on the Y axis, in degrees.

Place Ghost Recipe

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

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x37 0x39	Play	Client	Window ID	Byte VarInt
			Recipe	Identifier	A recipe ID.
			Recipe Display ID	VarInt	ID in the minecraft:recipe_display registry.
			Recipe Data	Varies	Depends on Recipe Type; see below.

below

Recipe Book Add

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x44	Play	Client	Recipe Count		VarInt		Number of elements in the following array.
			Recipes	Recipe ID	Array	VarInt	ID to assign to the recipe.
				Display ID		VarInt	ID in the minecraft:recipe_display registry.
				Group ID		VarInt
				Category ID		VarInt	ID in the minecraft:recipe_book_category registry.
				Has Ingredients		Boolean
				Ingredient Count		Optional VarInt	Number of elements in the following array. Only present if Has Ingredients is true.
				Ingredients		Optional Array of ID Set	Only present if Has Ingredients is true.
				Flags		Byte	0x01: show notification; 0x02: highlight as new
			Replace		Bool		Replace or Add to known recipes

Recipe Book Remove

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x45	Play	Client	Recipe Count	VarInt	Number of elements in the following array.
			Recipes	Array of VarInt	IDs of recipes to remove.

Recipe Book Settings

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x46	Play	Client	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.

Respawn

	The following information needs to be added to this page:
	Although the number of portal cooldown ticks is included in this packet, 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 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
0x47 0x4C	Play	Client	Dimension Type	VarInt	The ID of type of dimension in the minecraft:dimension_type registry, defined by the Registry Data packet.
			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.
			Sea level	VarInt
			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 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.

Set Cursor Item

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x5A	Play	Client	Slot Data	Slot

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.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x64 0x6b	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.
			Time of day increasing	Boolean	If true, the client should automatically advance the time of day according to its ticking rate.

Set Player Inventory Slot

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x66	Play	Client	Slot	VarInt
			Slot Data	Slot

Teleport Entity

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

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x70 0x77	Play	Client	Entity ID	VarInt
			X	Double
			Y	Double
			Z	Double
			Velocity X	Double
			Velocity Y	Double
			Velocity Z	Double
			Yaw	Angle Float	(Y Rot)New angle, not a delta.
			Pitch	Angle Float	(X Rot)New angle, not a delta.
			Flags	Teleport Flags
			On Ground	Boolean

Serverbound

Bundle Item Selected

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x02	Play	Server	Slot of Bundle	VarInt
			Slot in Bundle	VarInt

Client Tick End

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0B	Play	Server	no fields

Click Container

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

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x0E 0x10	Play	Server	Window ID		Unsigned Byte VarInt		The ID of the window which was clicked. 0 for player inventory. The server ignores any packets 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 packet.
			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 packet, 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 packets 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 packet which is sent as usual):

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

If any of the painting packets 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 packet is sent by the client when closing a window.

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

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0F 0x11	Play	Server	Window ID	Unsigned Byte VarInt	This is the ID of the window that was closed. 0 for player inventory.

Edit Book

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14 0x16	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 200 100.
			Entries	Array (200 100) of String (8192 1024)	Text from each page. Maximum string length is 8192 1024 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 32)	Title of book.

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 packets 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 packet) 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 packet) 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 packet 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.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1A 0x1C	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.
			Flags	Byte	Bit field: 0x01: on ground, 0x02: pushing against wall.

Set Player Position and Rotation

A combination of Move Player Rotation and Move Player Position.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1B 0x1D	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.
			Flags	Byte	Bit field: 0x01: on ground, 0x02: pushing against wall.

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)

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1C 0x1E	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.
			Flags	Byte	Bit field: 0x01: on ground, 0x02: pushing against wall.

Set Player On Ground Movement Flags

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

This packet 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 packets containing this state.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1D 0x1F	Play	Server	On Ground	Boolean	True if the client is on the ground, false otherwise.
			Flags	Byte	Bit field: 0x01: on ground, 0x02: pushing against wall.

Place Recipe

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

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22 0x24	Play	Server	Window ID	Byte
			Recipe ID	Identifier VarInt	A recipe ID. ID of recipe previously defined in Recipe Book Add.
			Make all	Boolean	Affects the amount of items processed; true if shift is down when clicked.

Player Input

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x26 0x28	Play	Server	Sideways	Float	Positive to the left of the player.
			Forward	Float	Positive forward.
			Flags	Unsigned Byte	Bit mask. 0x1: jump, 0x2: unmount. ; see below.

The flags are as follows:

Hex Mask	Field
0x01	Forward
0x02	Backward
0x04	Left
0x08	Right
0x10	Jump
0x20	Sneak
0x40	Sprint

Set Seen Recipe

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

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x29 0x2B	Play	Server	Recipe ID	Identifier VarInt	ID of recipe previously defined in Recipe Book Add.