Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.20.4, protocol 765) to the current pre-release (currently 24w03b, protocol Snapshot 172). 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

ID	Packet name	Documentation
Handshake serverbound
0x00	Handshake	Current	Pre
Login clientbound
0x05	Cookie Request (login)		Pre
Login serverbound
0x04	Cookie Response (login)		Pre
Configuration clientbound
0x00	Cookie Request (configuration)		Pre
0x00 0x01	Clientbound Plugin Message (configuration)	Current	(unchanged)
0x01 0x02	Disconnect (configuration)	Current	(unchanged)
0x02 0x03	Finish Configuration	Current	(unchanged)
0x03 0x04	Clientbound Keep Alive (configuration)	Current	(unchanged)
0x04 0x05	Ping (configuration)	Current	(unchanged)
0x05 0x06	Registry Data	Current	(unchanged)
0x06 0x07	Remove Resource Pack (configuration)	Current	(unchanged)
0x07 0x08	Add Resource Pack (configuration)	Current	(unchanged)
0x09	Store Cookie (configuration)		Pre
0x0A	Transfer (configuration)		Pre
0x08 0x0B	Feature Flags	Current	(unchanged)
0x09 0x0C	Update Tags (configuration)	Current	(unchanged)
Configuration serverbound
0x01	Cookie Response (configuration)		Pre
0x01 0x02	Serverbound Plugin Message (configuration)	Current	(unchanged)
0x02 0x03	Finish Configuration	Current	(unchanged)
0x03 0x04	Serverbound Keep Alive (configuration)	Current	(unchanged)
0x04 0x05	Pong (configuration)	Current	(unchanged)
0x05 0x06	Resource Pack Response (configuration)	Current	(unchanged)
Play clientbound
0x16	Cookie Request (Play)		Pre
0x16 0x17	Set Cooldown	Current	(unchanged)
0x17 0x18	Chat Suggestions	Current	(unchanged)
0x18 0x19	Clientbound Plugin Message (play)	Current	(unchanged)
0x19 0x1A	Damage Event	Current	(unchanged)
0x1A 0x1B	Delete Message	Current	(unchanged)
0x1B 0x1C	Disconnect (play)	Current	(unchanged)
0x1C 0x1D	Disguised Chat Message	Current	(unchanged)
0x1D 0x1E	Entity Event	Current	(unchanged)
0x1E 0x1F	Explosion	Current	(unchanged)
0x1F 0x20	Unload Chunk	Current	(unchanged)
0x20 0x21	Game Event	Current	(unchanged)
0x21 0x22	Open Horse Screen	Current	(unchanged)
0x22 0x23	Hurt Animation	Current	(unchanged)
0x23 0x24	Initialize World Border	Current	(unchanged)
0x24 0x25	Clientbound Keep Alive (play)	Current	(unchanged)
0x25 0x26	Chunk Data and Update Light	Current	(unchanged)
0x26 0x27	World Event	Current	(unchanged)
0x27 0x28	Particle	Current	(unchanged)
0x28 0x29	Update Light	Current	(unchanged)
0x29 0x2A	Login (play)	Current	(unchanged)
0x2A 0x2B	Map Data	Current	(unchanged)
0x2B 0x2C	Merchant Offers	Current	(unchanged)
0x2C 0x2D	Update Entity Position	Current	(unchanged)
0x2D 0x2E	Update Entity Position and Rotation	Current	(unchanged)
0x2E 0x2F	Update Entity Rotation	Current	(unchanged)
0x2F 0x30	Move Vehicle	Current	(unchanged)
0x30 0x31	Open Book	Current	(unchanged)
0x31 0x32	Open Screen	Current	(unchanged)
0x32 0x33	Open Sign Editor	Current	(unchanged)
0x33 0x34	Ping (play)	Current	(unchanged)
0x34 0x35	Ping Response (play)	Current	(unchanged)
0x35 0x36	Place Ghost Recipe	Current	(unchanged)
0x36 0x37	Player Abilities	Current	(unchanged)
0x37 0x38	Player Chat Message	Current	(unchanged)
0x38 0x39	End Combat	Current	(unchanged)
0x39 0x3A	Enter Combat	Current	(unchanged)
0x3A 0x3B	Combat Death	Current	(unchanged)
0x3B 0x3C	Player Info Remove	Current	(unchanged)
0x3C 0x3D	Player Info Update	Current	(unchanged)
0x3D 0x3E	Look At	Current	(unchanged)
0x3E 0x3F	Synchronize Player Position	Current	(unchanged)
0x3F 0x40	Update Recipe Book	Current	(unchanged)
0x40 0x41	Remove Entities	Current	(unchanged)
0x41 0x42	Remove Entity Effect	Current	(unchanged)
0x42 0x43	Reset Score	Current	(unchanged)
0x43 0x44	Remove Resource Pack (play)	Current	(unchanged)
0x44 0x45	Add Resource Pack (play)	Current	(unchanged)
0x45 0x46	Respawn	Current	(unchanged)
0x46 0x47	Set Head Rotation	Current	(unchanged)
0x47 0x48	Update Section Blocks	Current	(unchanged)
0x48 0x49	Select Advancements Tab	Current	(unchanged)
0x49 0x4A	Server Data	Current	(unchanged)
0x4A 0x4B	Set Action Bar Text	Current	(unchanged)
0x4B 0x4C	Set Border Center	Current	(unchanged)
0x4C 0x4D	Set Border Lerp Size	Current	(unchanged)
0x4D 0x4E	Set Border Size	Current	(unchanged)
0x4E 0x4F	Set Border Warning Delay	Current	(unchanged)
0x4F 0x50	Set Border Warning Distance	Current	(unchanged)
0x50 0x51	Set Camera	Current	(unchanged)
0x51 0x52	Set Held Item	Current	(unchanged)
0x52 0x53	Set Center Chunk	Current	(unchanged)
0x53 0x54	Set Render Distance	Current	(unchanged)
0x54 0x55	Set Default Spawn Position	Current	(unchanged)
0x55 0x56	Display Objective	Current	(unchanged)
0x56 0x57	Set Entity Metadata	Current	(unchanged)
0x57 0x58	Link Entities	Current	(unchanged)
0x58 0x59	Set Entity Velocity	Current	(unchanged)
0x59 0x5A	Set Equipment	Current	(unchanged)
0x5A 0x5B	Set Experience	Current	(unchanged)
0x5B 0x5C	Set Health	Current	(unchanged)
0x5C 0x5D	Update Objectives	Current	(unchanged)
0x5D 0x5E	Set Passengers	Current	(unchanged)
0x5E 0x5F	Update Teams	Current	(unchanged)
0x5F 0x60	Update Score	Current	(unchanged)
0x60 0x61	Set Simulation Distance	Current	(unchanged)
0x61 0x62	Set Subtitle Text	Current	(unchanged)
0x62 0x63	Update Time	Current	(unchanged)
0x63 0x64	Set Title Text	Current	(unchanged)
0x64 0x65	Set Title Animation Times	Current	(unchanged)
0x65 0x66	Entity Sound Effect	Current	(unchanged)
0x66 0x67	Sound Effect	Current	(unchanged)
0x67 0x68	Start Configuration	Current	(unchanged)
0x68 0x69	Stop Sound	Current	(unchanged)
0x6A	Store Cookie (Play)		Pre
0x69 0x6B	System Chat Message	Current	(unchanged)
0x6A 0x6C	Set Tab List Header And Footer	Current	(unchanged)
0x6B 0x6D	Tag Query Response	Current	(unchanged)
0x6C 0x6E	Pickup Item	Current	(unchanged)
0x6D 0x6F	Teleport Entity	Current	(unchanged)
0x6E 0x70	Set Ticking State	Current	(unchanged)
0x6F 0x71	Step Tick	Current	(unchanged)
0x72	Transfer (Play)		Pre
0x70 0x73	Update Advancements	Current	(unchanged)
0x71 0x74	Update Attributes	Current	Pre
0x72 0x75	Entity Effect	Current	Pre
0x73 0x76	Update Recipes	Current	(unchanged)
0x74 0x77	Update Tags (play)	Current	(unchanged)
Play serverbound
0x10	Cookie Response (play)		Pre
0x10 0x11	Serverbound Plugin Message (play)	Current	(unchanged)
0x11 0x12	Edit Book	Current	(unchanged)
0x12 0x13	Query Entity Tag	Current	(unchanged)
0x13 0x14	Interact	Current	(unchanged)
0x14 0x15	Jigsaw Generate	Current	(unchanged)
0x15 0x16	Serverbound Keep Alive (play)	Current	(unchanged)
0x16 0x17	Lock Difficulty	Current	(unchanged)
0x17 0x18	Set Player Position	Current	(unchanged)
0x18 0x19	Set Player Position and Rotation	Current	(unchanged)
0x19 0x1A	Set Player Rotation	Current	(unchanged)
0x1A 0x1B	Set Player On Ground	Current	(unchanged)
0x1B 0x1C	Move Vehicle	Current	(unchanged)
0x1C 0x1D	Paddle Boat	Current	(unchanged)
0x1D 0x1E	Pick Item	Current	(unchanged)
0x1E 0x1F	Ping Request (play)	Current	(unchanged)
0x1F 0x20	Place Recipe	Current	(unchanged)
0x20 0x21	Player Abilities	Current	(unchanged)
0x21 0x22	Player Action	Current	(unchanged)
0x22 0x23	Player Command	Current	(unchanged)
0x23 0x24	Player Input	Current	(unchanged)
0x24 0x25	Pong (play)	Current	(unchanged)
0x25 0x26	Change Recipe Book Settings	Current	(unchanged)
0x26 0x27	Set Seen Recipe	Current	(unchanged)
0x27 0x28	Rename Item	Current	(unchanged)
0x28 0x29	Resource Pack Response (play)	Current	(unchanged)
0x29 0x2A	Seen Advancements	Current	(unchanged)
0x2A 0x2B	Select Trade	Current	(unchanged)
0x2B 0x2C	Set Beacon Effect	Current	(unchanged)
0x2C 0x2D	Set Held Item	Current	(unchanged)
0x2D 0x2E	Program Command Block	Current	(unchanged)
0x2E 0x2F	Program Command Block Minecart	Current	(unchanged)
0x2F 0x30	Set Creative Mode Slot	Current	(unchanged)
0x30 0x31	Program Jigsaw Block	Current	(unchanged)
0x31 0x32	Program Structure Block	Current	(unchanged)
0x32 0x33	Update Sign	Current	(unchanged)
0x33 0x34	Swing Arm	Current	(unchanged)
0x34 0x35	Teleport To Entity	Current	(unchanged)
0x35 0x36	Use Item On	Current	(unchanged)
0x36 0x37	Use Item	Current	(unchanged)

New/modified data types

No changes so far.

Entity Metadata

Type (VarInt Enum)	Value (Varies)	Notes
0	Byte
1	VarInt
2	VarLong
3	Float
4	String
5	Chat
6	OptChat (Boolean + Chat)	Chat is present if the Boolean is set to true
7	Slot
8	Boolean
9	Rotation	3 Floats: rotation on x, rotation on y, rotation on z
10	Position
11	OptPosition (Boolean + Position)	Position is present if the Boolean is set to true
12	Direction (VarInt)	(Down = 0, Up = 1, North = 2, South = 3, West = 4, East = 5)
13	OptUUID (Boolean + UUID)	UUID is present if the Boolean is set to true
14	BlockID (VarInt)
15	OptBlockID (VarInt)	0 for absent (implies air); otherwise, a block state ID as per the block state registry
16	NBT
17	Particle
18	Villager Data	3 VarInts: villager type, villager profession, level
19	OptVarInt	0 for absent; 1 + actual value otherwise. Used for entity IDs.
20	Pose	A VarInt enum: 0: STANDING, 1: FALL_FLYING, 2: SLEEPING, 3: SWIMMING, 4: SPIN_ATTACK, 5: SNEAKING, 6: LONG_JUMPING, 7: DYING, 8: CROAKING, 9: USING_TONGUE, 10: SITTING, 11: ROARING, 12: SNIFFING, 13: EMERGING, 14: DIGGING, 15: SLIDING, 16: SHOOTING, 17: INHALING
21	Cat Variant	A VarInt that points towards the CAT_VARIANT registry.
22	Frog Variant	A VarInt that points towards the FROG_VARIANT registry.
23	OptGlobalPos (Boolean + GlobalPos)	GlobalPos consists of a dimension identifier and Position.
24	Painting Variant	A VarInt that points towards the PAINTING_VARIANT registry.
25	Sniffer State	A VarInt enum: IDLING = 0, FEELING_HAPPY = 1, SCENTING = 2, SNIFFING = 3, SEARCHING = 4, DIGGING = 5, RISING = 6
26	Armadillo State	A VarInt enum: IDLE = 0, ROLLING = 1, SCARED = 2
26 27	Vector3	3 Floats: x, y, z
27 28	Quaternion	4 Floats: x, y, z, w

Armadillo

Extends Animal.

Index	Type	Meaning		Default
17	Armadillo State	Armadillo State		IDLE

Block Actions

No changes so far.

Inventories

No changes so far.

Plugin Channels

No changes so far.

Handshake

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Handshaking	Server	Protocol Version	VarInt	See protocol version numbers (currently 765 in Minecraft 1.20.4).
			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.

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

Cookie Request (login)

Requests a cookie that was previously stored.

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

Serverbound

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.

Packet 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		Optional ByteArray(5120)		The data of the cookie, if any.

Configuration

Clientbound

Cookie Request (configuration)

Requests a cookie that was previously stored.

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

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.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x09	Configuration	Client	Key		Identifier		The identifier of the cookie.
			Payload		ByteArray(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.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x0A	Configuration	Client	Host		String		The hostname of IP of the server.
			Port		VarInt		The port of the server.

Serverbound

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.

Packet 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		Optional ByteArray(5120)		The data of the cookie, if any.

Play

Clientbound

Cookie Request (play)

Requests a cookie that was previously stored.

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

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.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x6A	Play	Client	Key		Identifier		The identifier of the cookie.
			Payload		ByteArray(5120)		The data of the cookie.

Transfer (play)

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

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x72	Play	Client	Host		String		The hostname of IP of the server.
			Port		VarInt		The port of the server.

Update Attributes

Sets attributes on the given entity.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x71	Play	Client	Entity ID		VarInt
			Number Of Properties		VarInt		Number of elements in the following array.
			Property	Key Id	Array	Identifier 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 Key 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_interaction_range	4.5	0.0	64.0	Block Interaction Range.
6	generic.entity_interaction_range	3.0	0.0	64.0	Entity Interaction Range.
7	generic.flying_speed	0.4	0.0	1024.0	Flying Speed.
8	generic.follow_range	32.0	0.0	2048.0	Follow Range.
9	horse.jump_strength	0.7	0.0	2.0	Jump Strength.
10	generic.knockback_resistance	0.0	0.0	1.0	Knockback Resistance.
11	generic.luck	0.0	-1024.0	1024.0	Luck.
12	generic.max_absorption	0.0	0.0	2048.0	Max Absorption.
13	generic.max_health	20.0	1.0	1024.0	Max Health.
14	generic.movement_speed	0.7	0.0	1024.0	Movement Speed.
15	generic.scale	1.0	0.0625	16.0	Scale.
16	zombie.spawn_reinforcements	0.0	0.0	1.0	Spawn Reinforcements Chance.
17	generic.step_height	0.6	0.0	10.0	Step Height.

Modifier Data structure:

Field Name	Field Type	Notes
UUID	UUID
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

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x72	Play	Client	Entity ID	VarInt
			Effect ID	VarInt	See this table.
			Amplifier	Byte	Notchian client displays effect level as Amplifier + 1.
			Duration	VarInt	Duration in ticks. (-1 for infinite)
			Flags	Byte	Bit field, see below.
			Has Factor Data	Boolean	Used in DARKNESS effect
			Factor Codec	NBT Tag	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.

Factor Data

Name	Type	Notes
padding_duration	TAG_INT
factor_start	TAG_FLOAT
factor_target	TAG_FLOAT
factor_current	TAG_FLOAT
effect_changed_timestamp	TAG_INT
factor_previous_frame	TAG_FLOAT
had_effect_last_tick	TAG_BOOLEAN

Serverbound

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.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x6A	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		Optional ByteArray(5120)		The data of the cookie, if any.