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
{{#switch: Pre-release protocol	Data types = ID Set	#default = ID Set }}	Varies	Set of registry IDs specified either inline or as a reference to a tag.	See #ID Set

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	{{#switch: Pre-release protocol	Data types = VarInt	#default = 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	{{#switch: Pre-release protocol	Data types = Optional	#default = Optional }} {{#switch: Pre-release protocol	Data types = Identifier	#default = Identifier }}	The registry tag defining the ID set. Only present if Type is 0.
IDs	{{#switch: Pre-release protocol	Data types = Optional	#default = Optional }} {{#switch: Pre-release protocol	Data types = Array	#default = Array }} of {{#switch: Pre-release protocol	Data types = VarInt	#default = 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
0x20	Synchronize Entity Position	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x31	Move Minecart Along Track	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x41	Update Recipe Book	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x43	Player Rotation	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x44	Recipe Book Add	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x45	Recipe Book Remove	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x46	Recipe Book Settings	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x53}}{{#if:0x63|{{#if:0x53| }}0x63}}	Set Held Item	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x5a	Set Cursor Item	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x66	Set Player Inventory Slot	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
Play serverbound
0x02	Bundle Item Selected	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}
0x0b	Client Tick End	added	Current }}	removed	unchanged | (unchanged) | Pre }} }}

Handshake

No changes so far.

Status

No changes so far.

Login

No changes so far.

Configuration

No changes so far.

Play

Clientbound

Synchronize Entity Position

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Teleport ID	{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}	Client should confirm this packet with Confirm Teleportation containing the same Teleport ID.
			X	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
			Y	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
			Z	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
			Velocity X	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
			Velocity Y	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
			Velocity Z	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
			Yaw	{{#switch: Pre-release protocol	Data types = Float	#default = Float }}	Rotation on the X axis, in degrees.
			Pitch	{{#switch: Pre-release protocol	Data types = Float	#default = Float }}	Rotation on the Y axis, in degrees.
			On Ground	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}

Move Minecart Along Track

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x31	Play	Client	Entity ID		{{#switch: Pre-release protocol		Data types = VarInt	#default = VarInt }}
			Step Count		{{#switch: Pre-release protocol		Data types = VarInt	#default = VarInt }}	Number of elements in the following array.
			Steps	X	{{#switch: Pre-release protocol	Data types = Array	#default = Array }}	{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
				Y		{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
				Z		{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
				Velocity X		{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
				Velocity Y		{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
				Velocity Z		{{#switch: Pre-release protocol	Data types = Double	#default = Double }}
				Yaw		{{#switch: Pre-release protocol	Data types = Angle	#default = Angle }}
				Pitch		{{#switch: Pre-release protocol	Data types = Angle	#default = Angle }}
				Weight		{{#switch: Pre-release protocol	Data types = Float	#default = Float }}

Player Rotation

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x43	Play	Client	Yaw	{{#switch: Pre-release protocol	Data types = Float	#default = Float }}	Rotation on the X axis, in degrees.
			Pitch	{{#switch: Pre-release protocol	Data types = Float	#default = Float }}	Rotation on the Y axis, in degrees.

Recipe Book Add

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x44	Play	Client	Recipe Count		{{#switch: Pre-release protocol		Data types = VarInt	#default = VarInt }}	Number of elements in the following array.
			Recipes	Recipe ID	{{#switch: Pre-release protocol	Data types = Array	#default = Array }}	{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}	ID to assign to the recipe.
				Display ID		{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}	ID in the minecraft:recipe_display registry.
				Group ID		{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}
				Category ID		{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}	ID in the minecraft:recipe_book_category registry.
				Has Ingredients		{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}
				Ingredient Count		{{#switch: Pre-release protocol	Data types = Optional	#default = Optional }} {{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}	Number of elements in the following array. Only present if Has Ingredients is true.
				Ingredients		{{#switch: Pre-release protocol	Data types = Optional	#default = Optional }} {{#switch: Pre-release protocol	Data types = Array	#default = Array }} of {{#switch: Pre-release protocol	Data types = ID Set	#default = ID Set }}	Only present if Has Ingredients is true.
			Flags		{{#switch: Pre-release protocol		Data types = Byte	#default = Byte }}	0x01: show notification; 0x02: hightlight as new

Recipe Book Remove

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x45	Play	Client	Recipe Count	{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}	Number of elements in the following array.
			Recipes	{{#switch: Pre-release protocol	Data types = Array	#default = Array }} of {{#switch: Pre-release protocol	Data types = VarInt	#default = 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	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the crafting recipe book will be open when the player opens its inventory.
			Crafting Recipe Book Filter Active	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the filtering option is active when the players opens its inventory.
			Smelting Recipe Book Open	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the smelting recipe book will be open when the player opens its inventory.
			Smelting Recipe Book Filter Active	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the filtering option is active when the players opens its inventory.
			Blast Furnace Recipe Book Open	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the blast furnace recipe book will be open when the player opens its inventory.
			Blast Furnace Recipe Book Filter Active	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the filtering option is active when the players opens its inventory.
			Smoker Recipe Book Open	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the smoker recipe book will be open when the player opens its inventory.
			Smoker Recipe Book Filter Active	{{#switch: Pre-release protocol	Data types = Boolean	#default = Boolean }}	If true, then the filtering option is active when the players opens its inventory.

Set Cursor Item

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x5A	Play	Client	Slot Data	{{#switch: Pre-release protocol	Data types = Slot	#default = Slot }}

Set Player Inventory Slot

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x66	Play	Client	Slot	{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}
			Slot Data	{{#switch: Pre-release protocol	Data types = Slot	#default = Slot }}

Serverbound

Bundle Item Selected

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x02	Play	Server	Slot of Bundle	{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}
			Slot in Bundle	{{#switch: Pre-release protocol	Data types = VarInt	#default = VarInt }}

Client Tick End

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