Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.15.2, protocol 578) to the current pre-release (currently 20w29a, protocol 741). 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

The UUID type is now also sometimes encoded by the Notchian server as an array of four 32-bit integers, from most significant to least significant (matching the new format used on entity NBT). This representation is identical to using 16 bytes, two 64-bit integers, or one 128-bit integers.

Packets

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre
Play clientbound
0x02	Spawn Weather Entity	Current
0x03 0x02	Spawn Living Entity	Current	(unchanged)
0x04 0x03	Spawn Painting	Current	(unchanged)
0x05 0x04	Spawn Player	Current	(unchanged)
0x06 0x05	Entity Animation (clientbound)	Current	(unchanged)
0x07 0x06	Statistics	Current	(unchanged)
0x08 0x07	Acknowledge Player Digging	Current	(unchanged)
0x09 0x08	Block Break Animation	Current	(unchanged)
0x0A 0x09	Block Entity Data	Current	(unchanged)
0x0B 0x0A	Block Action	Current	(unchanged)
0x0C 0x0B	Block Change	Current	(unchanged)
0x0D 0x0C	Boss Bar	Current	(unchanged)
0x0E 0x0D	Server Difficulty	Current	(unchanged)
0x0F 0x0E	Chat Message (clientbound)	Current	Pre
0x11 0x09	Tab-Complete (clientbound)	Current	(unchanged)
0x12 0x10	Declare Commands	Current	(unchanged)
0x13 0x11	Window Confirmation (clientbound)	Current	(unchanged)
0x14 0x12	Close Window (clientbound)	Current	(unchanged)
0x15 0x13	Window Items	Current	(unchanged)
0x16 0x14	Window Property	Current	(unchanged)
0x17 0x15	Set Slot	Current	(unchanged)
0x18 0x16	Set Cooldown	Current	(unchanged)
0x19 0x17	Plugin Message (clientbound)	Current	(unchanged)
0x1A 0x18	Named Sound Effect	Current	(unchanged)
0x1B 0x19	Disconnect (play)	Current	(unchanged)
0x1C 0x1A	Entity Status	Current	(unchanged)
0x1D 0x1B	Explosion	Current	(unchanged)
0x1E 0x1C	Unload Chunk	Current	(unchanged)
0x1F 0x1D	Change Game State	Current	(unchanged)
0x20 0x1E	Open Horse Window	Current	(unchanged)
0x21 0x1F	Keep Alive (clientbound)	Current	(unchanged)
0x22 0x20	Chunk Data	Current	Pre
0x23 0x21	Effect	Current	(unchanged)
0x24 0x22	Particle	Current	(unchanged)
0x25 0x23	Update Light	Current	Pre
0x26 0x24	Join Game	Current	Pre
0x27 0x25	Map Data	Current	(unchanged)
0x28 0x26	Trade List	Current	(unchanged)
0x29 0x27	Entity Position	Current	(unchanged)
0x2A 0x28	Entity Position and Rotation	Current	(unchanged)
0x2B 0x29	Entity Rotation	Current	(unchanged)
0x2C 0x2A	Entity Movement	Current	(unchanged)
0x2D 0x2B	Vehicle Move (clientbound)	Current	(unchanged)
0x2E 0x2C	Open Book	Current	(unchanged)
0x2F 0x2D	Open Window	Current	(unchanged)
0x30 0x2E	Open Sign Editor	Current	(unchanged)
0x31 0x2F	Craft Recipe Response	Current	(unchanged)
0x32 0x30	Player Abilities (clientbound)	Current	(unchanged)
0x33 0x31	Combat Event	Current	(unchanged)
0x34 0x32	Player Info	Current	(unchanged)
0x35 0x33	Face Player	Current	(unchanged)
0x36 0x34	Player Position And Look (clientbound)	Current	(unchanged)
0x37 0x35	Unlock Recipes	Current	Pre
0x38 0x36	Destroy Entities	Current	(unchanged)
0x39 0x37	Remove Entity Effect	Current	(unchanged)
0x3A 0x38	Resource Pack Send	Current	(unchanged)
0x3B 0x39	Respawn	Current	Pre
0x3C 0x3A	Entity Head Look	Current	(unchanged)
0x10 0x3B	Multi Block Change	Current	Pre
0x3D 0x3C	Select Advancement Tab	Current	(unchanged)
0x3E 0x3D	World Border	Current	(unchanged)
0x3F 0x3E	Camera	Current	(unchanged)
0x40 0x3F	Held Item Change (clientbound)	Current	(unchanged)
0x41 0x40	Update View Position	Current	(unchanged)
0x42 0x41	Update View Distance	Current	(unchanged)
0x47	Entity Equipment	Current	Pre
0x4E 0x42	Spawn Position	Current	(unchanged)
0x4F 0x4E	Time Update	Current	(unchanged)
0x50 0x4F	Title	Current	(unchanged)
0x51 0x50	Entity Sound Effect	Current	(unchanged)
0x52 0x51	Sound Effect	Current	(unchanged)
0x53 0x52	Stop Sound	Current	(unchanged)
0x54 0x53	Player List Header And Footer	Current	(unchanged)
0x55 0x54	NBT Query Response	Current	(unchanged)
0x56 0x55	Collect Item	Current	(unchanged)
0x57 0x56	Entity Teleport	Current	(unchanged)
0x58 0x57	Advancements	Current	(unchanged)
0x59 0x58	Entity Properties	Current	Pre
0x5A 0x59	Entity Effect	Current	(unchanged)
0x5B 0x5A	Declare Recipes	Current	Pre
0x5C 0x5B	Tags	Current	(unchanged)
Play serverbound
0x0E	Interact Entity	Current	Pre
0x0F	Generate Structure		Pre
0x0F 0x10	Keep Alive (serverbound)	Current	(unchanged)
0x10 0x11	Lock Difficulty	Current	(unchanged)
0x11 0x12	Player Position	Current	(unchanged)
0x12 0x13	Player Position And Rotation (serverbound)	Current	(unchanged)
0x13 0x14	Player Rotation	Current	(unchanged)
0x14 0x15	Player Movement	Current	(unchanged)
0x15 0x16	Vehicle Move (serverbound)	Current	(unchanged)
0x16 0x17	Steer Boat	Current	(unchanged)
0x17 0x18	Pick Item	Current	(unchanged)
0x18 0x19	Craft Recipe Request	Current	(unchanged)
0x19 0x1A	Player Abilities (serverbound)	Current	Pre
0x1A 0x1B	Player Digging	Current	(unchanged)
0x1B 0x1C	Entity Action	Current	(unchanged)
0x1C 0x1D	Steer Vehicle	Current	(unchanged)
0x1D	Recipe Book Data	Current
0x1E	Set Displayed Recipe		Pre
0x1F	Set Recipe Book State		Pre
0x1E 0x20	Name Item	Current	(unchanged)
0x1F 0x21	Resource Pack Status	Current	(unchanged)
0x20 0x22	Advancement Tab	Current	(unchanged)
0x21 0x23	Select Trade	Current	(unchanged)
0x22 0x24	Set Beacon Effect	Current	(unchanged)
0x23 0x25	Held Item Change (serverbound)	Current	(unchanged)
0x24 0x26	Update Command Block	Current	(unchanged)
0x25 0x27	Update Command Block Minecart	Current	(unchanged)
0x26 0x28	Creative Inventory Action	Current	(unchanged)
0x27 0x29	Update Jigsaw Block	Current	Pre
0x28 0x2A	Update Structure Block	Current	(unchanged)
0x29 0x2B	Update Sign	Current	(unchanged)
0x2A 0x2C	Animation (serverbound)	Current	(unchanged)
0x2B 0x2D	Spectate	Current	(unchanged)
0x2C 0x2E	Player Block Placement	Current	(unchanged)
0x2D 0x2F	Use Item	Current	(unchanged)
Login clientbound
0x02	Login Success	Current	Pre

New/modified data types

No changes so far.

Entity Metadata

FishingHook

Extends Entity.

Index	Type	Meaning		Default
7	VarInt	Hooked entity id + 1, or 0 if there is no hooked entity		0
8	Boolean	Is catchable		False

Abstract Arrow

Extends Entity.

Abstract base class for Tipped Arrow (which is used for regular arrows as well as tipped ones) and Spectral Arrow.

Index	Type	Meaning		Default
7	Byte	Bit mask	Meaning	0
		0x01	Is critical
		0x02	Is noclip (used by loyalty tridents when returning)
8	OptUUID	Unused		Empty
9 8	Byte	Peircing level		0

Tipped Arrow

Extends Abstract Arrow.

Used for both tipped and regular arrows. If not tipped, then color is set to -1 and no tipped arrow particles are used.

Index	Type	Meaning		Default
10 9	VarInt	Color (-1 for no particles)		-1

Spectral Arrow

Extends Abstract Arrow.

No additional metadata.

Trident

Extends Abstract Arrow.

Index	Type	Meaning		Default
10 9	VarInt	Loyalty level (enchantment)		0
11 10	Boolean	Has enchantment glint		False

Strider

Extends Animal.

Index	Type	Meaning		Default
16	VarInt	Total time to "boost" with warped fungus on a stick for		0
17	Boolean	Is shaking (true unless riding a vehicle or on or in a block tagged with strider_warm_blocks (default: lava))		false
18	Boolean	Has saddle		false

Hoglin

Extends Animal.

Index	Type	Meaning		Default
16	Boolean	Is immune to zombification		false

Zoglin

Extends Monster.

Index	Type	Meaning		Default
15	Boolean	Is baby		false

Base Piglin

Extends Monster.

Index	Type	Meaning		Default
15	Boolean	Is immune to zombification		false

Piglin

Extends Base Piglin.

Index	Type	Meaning		Default
16	Boolean	Is baby		false
17	Boolean	Is charging crossbow		false
18	Boolean	Is dancing		false

Piglin Brute

Extends Base Piglin.

No additional metadata.

Wolf

Extends TameableAnimal.

Index	Type	Meaning		Default
18	Boolean	Is begging		false
19	VarInt	Collar color (values are those used with dyes)		14 (Red)
20	VarInt	Anger time		0

Zombie Pigman Zombified Piglin

Extends Zombie.

No additional metadata.

Block Actions

No changes so far.

Inventories

No changes so far.

Plugin Channels

No changes so far.

Play

Clientbound

Chat Message (clientbound)

Identifying the difference between Chat/System Message is important as it helps respect the user's chat visibility options. See processing chat for more info about these positions.

Game info accepts json formatting but does not display it, although the deprecated §-based formatting works. This is not an issue when using the Title packet, so prefer that packet for displaying information in that slot. See MC-119145 for more information.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0F 0x0E	Play	Client	JSON Data	Chat	Limited to 32767 bytes
			Position	Byte	0: chat (chat box), 1: system message (chat box), 2: game info (above hotbar).
			Sender	UUID	Used by the Notchian client for the disableChat launch option. Setting both longs to 0 will always display the message regardless of the setting.

Chunk Data

Main article: Chunk Format

See also: #Unload Chunk

	The following information needs to be added to this page:
	How do biomes work now? The biome change happened at the same time as the seed change, but it's not clear how/if biomes could be computed given that it's not the actual seed... (/r/mojira discussion which notes that it seems to be some kind of interpolation, and 3D biomes are only used in the nether)

The server only sends skylight information for chunk pillars in the Overworld, it's up to the client to know in which dimenison the player is currently located. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent. This packet also sends all block entities in the chunk (though sending them is not required; it is still legal to send them with Update Block Entity later).

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22 0x20	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Ignore old data	Boolean	If false, the client will recalculate lighting based on the old/new chunk data
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Heightmaps	NBT	Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries at 9 bits per entry totaling 36 longs). The Notchian server also adds a WORLD_SURFACE long array, the purpose of which is unknown, but it's not required for the chunk to be accepted.
			Biomes length	Optional VarInt	Size of the following array. Not present if full chunk is false.
			Biomes	Optional array of Integer VarInt	1024 biome IDs, ordered by x then z then y, in 4×4×4 blocks. Possibly something else. Not present if full chunk is false.
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.

Note that the Notchian client requires an Update View Position packet when it crosses a chunk border, otherwise it'll only display render distance + 2 chunks around the chunk it spawned in.

The compacted array format has been adjusted so that individual entries no longer span across multiple longs, affecting the main data array and heightmaps.

Update Light

Updates light levels for a chunk.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x25 0x23	Play	Client	Chunk X		VarInt		Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z		VarInt		Chunk coordinate (block coordinate divided by 16, rounded down)
			Trust Edges		Boolean		If edges should be trusted for light updates.
			Sky Light Mask		VarInt		Mask containing 18 bits, with the lowest bit corresponding to chunk section -1 (in the void, y=-16 to y=-1) and the highest bit for chunk section 16 (above the world, y=256 to y=271)
			Block Light Mask		VarInt		Mask containing 18 bits, with the same order as sky light
			Empty Sky Light Mask		VarInt		Mask containing 18 bits, which indicates sections that have 0 for all their sky light values. If a section is set in both this mask and the main sky light mask, it is ignored for this mask and it is included in the sky light arrays (the notchian server does not create such masks). If it is only set in this mask, it is not included in the sky light arrays.
			Empty Block Light Mask		VarInt		Mask containing 18 bits, which indicates sections that have 0 for all their block light values. If a section is set in both this mask and the main block light mask, it is ignored for this mask and it is included in the block light arrays (the notchian server does not create such masks). If it is only set in this mask, it is not included in the block light arrays.
			Sky Light arrays	Length	Array	VarInt	Length of the following array in bytes (always 2048)
				Sky Light array		Array of 2048 bytes	There is 1 array for each bit set to true in the sky light mask, starting with the lowest value. Half a byte per light value.
			Block Light arrays	Length	Array	VarInt	Length of the following array in bytes (always 2048)
				Block Light array		Array of 2048 bytes	There is 1 array for each bit set to true in the block light mask, starting with the lowest value. Half a byte per light value.

Individual block or sky light arrays are is given for each block with increasing x coordinates, within rows of increasing z coordinates, within layers of increasing y coordinates. Even-indexed items (those with an even x coordinate, starting at 0) are packed into the low bits, odd-indexed into the high bits.

Join Game

See Protocol Encryption for information on logging in.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x26 0x24	Play	Client	Entity ID	Int	The player's Entity ID (EID)
			Is hardcore	Boolean
			Gamemode	Unsigned Byte	0: Survival, 1: Creative, 2: Adventure, 3: Spectator. Bit 3 (0x8) is the hardcore flag.
			Previous Gamemode	Unsigned Byte	0: survival, 1: creative, 2: adventure, 3: spectator. The hardcore flag is not included. The previous gamemode. (More information needed)
			World Count	VarInt	Size of the following array
			World Names	Array of Identifier	Identifiers for all worlds on the server
			Dimension Codec	NBT Tag Compound	The full extent of these is still unknown, but the tag represents a dimension and biome registry. See below for the vanilla default.
			Dimension	Int Enum Identifier	-1: The Nether, 0: The Overworld, 1: The End Valid dimensions are defined per dimension registry sent before this
			World Name	Identifier	Name of the world being spawned into
			Hashed seed	Long	First 8 bytes of the SHA-256 hash of the world's seed.
			Max Players	Unsigned Byte	Was once used by the client to draw the player list, but now is ignored
			Level Type	String Enum (16)	default, flat, largeBiomes, amplified, customized, buffet, default_1_1
			View Distance	VarInt	Render distance (2-32)
			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
			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

	The following information needs to be added to this page:
	The format has changed in 20w28a

Example of Dimension codec CompoundTag sent by the server:

   ListTag (Type: CompoundTag) "dimension":
       CompoundTag: 
           StringTag "name" value: 'minecraft:overworld'
           ByteTag "natural": 1
           Some more attributes ...

Known attributes :

Name	Type	Meaning		Values
name	String	Dimension's name		"minecraft:overworld", "minecraft:the_nether", "minecraft:the_end" or something else
natural	Byte	Is it a standard overworld like dimension		1: true, 0: false
ambient_light	Float	Ambient light		0.0 to 1.0
has_ceiling	Byte	Does the dimension have blocks on top ? Like the nether		1: true, 0: false
has_skylight	Byte	Does the dimension have natural sky light		1: true, 0: false
fixed_time	Long	Set fixed minecraft clock time		0 to 12000
shrunk	Byte	?		1: true, 0: false
ultrawarm	Byte	?		1: true, 0: false
has_raids	Byte	?		1: true, 0: false
respawn_anchor_works	Byte	Wether or not respawn anchor can be used		1: true, 0: false
bed_works	Byte	Wether or not beds can be used		1: true, 0: false
piglin_safe	Byte	?		1: true, 0: false
logical_height	Int	Maybe the world's max height in blocks ?		0-256
infiniburn	String	?		"" or minecraft resource "minecraft:..."

Unlock Recipes

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x37 0x35	Play	Client
			Action	VarInt	0: init, 1: add, 2: remove
			Crafting Recipe Book Open	Boolean	If true, then the crafting recipe book will be open when the player opens its inventory.
			Crafting Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Smelting Recipe Book Open	Boolean	If true, then the smelting recipe book will be open when the player opens its inventory.
			Smelting Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Blast Furance Recipe Book Open	Boolean	If true, then the blast furnace recipe book will be open when the player opens its inventory.
			Blast Furance Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Smoker Recipe Book Open	Boolean	If true, then the smoker recipe book will be open when the player opens its inventory.
			Smoker Recipe Book Filter Active	Boolean	If true, then the filtering option is active when the players opens its inventory.
			Array size 1	VarInt	Number of elements in the following array
			Recipe IDs	Array of Identifier
			Array size 2	Optional VarInt	Number of elements in the following array, only present if mode is 0 (init)
			Recipe IDs	Optional Array of Identifier, only present if mode is 0 (init)

Action:

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

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
0x3B 0x39	Play	Client	Dimension	Int Enum Identifier	-1: The Nether, 0: The Overworld, 1: The End Valid dimensions are defined per dimension registry sent in Join Game
			World Name	Identifier	Name of the world being spawned into
			Hashed seed	Long	First 8 bytes of the SHA-256 hash of the world's seed.
			Gamemode	Unsigned Byte	0: survival, 1: creative, 2: adventure, 3: spectator. The hardcore flag is not included
			Previous Gamemode	Unsigned Byte	0: survival, 1: creative, 2: adventure, 3: spectator. The hardcore flag is not included. The previous gamemode. (More information needed)
			Level Type	String (16)	Same as Join Game
			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
			Copy metadata	Boolean	If false, metadata is reset on the respawned player entity. Set to true for dimension changes (including the dimension change triggered by sending client status perform respawn to exit the end poem/credits), and false for normal respawns.

	The following information needs to be added to this page:
	Does the new World Name field resolve this same-dimension issue?

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).

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.

Multi Block Change

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x10 0x3B	Play	Client		Long	Chunk section coordinate (encoded chunk x and z with each 22 bits, and section y with 20 bits, from left to right)
			Array size	VarInt	Number of elements in the following array
				Array of VarLong	Each entry is composed of the block id, shifted right by 12, and the relative block position in the chunk section (4 bits for x, z, and y, from left to right).

Entity Properties

Sets attributes on the given entity.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x59 0x58	Play	Client	Entity ID		VarInt
			Number Of Properties		Int		Number of elements in the following array
			Property	Key	Array	String (64) Identifier	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):

Key	Default	Min	Max	Label
generic.maxHealth generic.max_health	20.0	0.0	1024.0	Max Health
generic.followRange generic.follow_range	32.0	0.0	2048.0	Follow Range
generic.knockbackResistance generic.knockback_resistance	0.0	0.0	1.0	Knockback Resistance
generic.movementSpeed generic.movement_speed	0.7	0.0	1024.0	Movement Speed
generic.attackDamage generic.attack_damage	2.0	0.0	2048.0	Attack Damage
generic.attackSpeed generic.attack_speed	4.0	0.0	1024.0	Attack Speed
generic.flyingSpeed generic.flying_speed	0.4	0.0	1024.0	Flying Speed
generic.armor	0.0	0.0	30.0	Armor
generic.armorToughness generic.armor_toughness	0.0	0.0	20.0	Armor Toughness
generic.attackKnockback generic.attack_knockback	0.0	0.0	5.0	—
generic.luck	0.0	-1024.0	1024.0	Luck
horse.jumpStrength horse.jump_strength	0.7	0.0	2.0	Jump Strength
zombie.spawnReinforcements zombie.spawn_reinforcements	0.0	0.0	1.0	Spawn Reinforcements Chance
generic.reachDistance	5.0	0.0	1024.0	Player Reach Distance (Forge only)
forge.swimSpeed	1.0	0.0	1024.0	Swimming Speed (Forge only)

Unknown attributes will cause a game crash (MC-150405) due to the default minimum being larger than the default value.

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.

Declare Recipes

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x5B 0x5A	Play	Client	Num Recipes		VarInt		Number of elements in the following array
			Recipe	Recipe ID	Array	Identifier
				Type		String	The recipe type, see below
				Data		Optional, varies	Additional data for the recipe. For some types, there will be no data.

Recipe types:

Type	Description	Data
crafting_shapeless	Shapeless crafting recipe. All items in the ingredient list must be present, but in any order/slot.	As follows: Name Type Description Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Ingredient count VarInt Number of elements in the following array Ingredients Array of Ingredient Result Slot
crafting_shaped	Shaped crafting recipe. All items must be present in the same pattern (which may be flipped horizontally or translated)	As follows: Name Type Description Width VarInt Height VarInt Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Ingredients Array of Ingredient Length is width * height. Indexed by x + (y * width). Result Slot
crafting_special_armordye	Recipe for dying leather armor	None
crafting_special_bookcloning	Recipe for copying contents of written books
crafting_special_mapcloning	Recipe for copying maps
crafting_special_mapextending	Recipe for adding paper to maps
crafting_special_firework_rocket	Recipe for making firework rockets
crafting_special_firework_star	Recipe for making firework stars
crafting_special_firework_star_fade	Recipe for making firework stars fade between multiple colors
crafting_special_repairitem	Recipe for repairing items via crafting
crafting_special_tippedarrow	Recipe for crafting tipped arrows
crafting_special_bannerduplicate	Recipe for copying banner patterns
crafting_special_banneraddpattern	Recipe for adding patterns to banners
crafting_special_shielddecoration	Recipe for applying a banner's pattern to a shield
crafting_special_shulkerboxcoloring	Recipe for recoloring a shulker box
smelting	Smelting recipe	As follows: Name Type Description Group String Used to group similar recipes together in the recipe book. Ingredient Ingredient Result Slot Experience Float Cooking time VarInt
blasting	Blast furnace recipe
smoking	Smoker recipe
campfire_cooking	Campfire recipe
stonecutting	Stonecutter recipe	As follows: Name Type Description Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON. Ingredient Ingredient Result Slot
smithing	Smithing table recipe	As follows: Name Type Description Base Ingredient First item Addition Ingredient Second item Result Slot

Ingredient is defined as:

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

Serverbound

Interact Entity

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

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

Note that middle-click in creative mode is interpreted by the client and sent as a Creative Inventory Action packet instead.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0E	Play	Server	Entity ID	VarInt	The ID of the entity to interact
			Type	VarInt Enum	0: interact, 1: attack, 2: interact at
			Target X	Optional Float	Only if Type is interact at
			Target Y	Optional Float	Only if Type is interact at
			Target Z	Optional Float	Only if Type is interact at
			Hand	Optional VarInt Enum	Only if Type is interact or interact at; 0: main hand, 1: off hand
			Sneaking	Boolean	If the client is sneaking.

Generate Structure

Sent when Generate is pressed on the Jigsaw Block interface.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0F	Play	Server	Location	Position	Block entity location
			Levels	VarInt	Value of the levels slider/max depth to generate
			Keep Jigsaws	Boolean

Player Abilities (serverbound)

The latter 2 fields are used to indicate the walking and flying speeds respectively, while the first field is used to determine the value of 4 booleans.

The vanilla client sends this packet when the player starts/stops flying with the Flags parameter changed accordingly. All other parameters are ignored by the vanilla server.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x19 0x1A	Play	Server	Flags	Byte	Bit mask. 0x08: damage disabled (god mode), 0x04: can fly, 0x02: is flying, 0x01: is Creative
			Flying Speed	Float
			Walking Speed	Float

Set Displayed Recipe

Replaces Recipe Book Data, type 0.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1E	Play	Server	Recipe ID	Identifier

Set Recipe Book State

Replaces Recipe Book Data, type 1.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1F	Play	Server	Book ID	VarInt enum	0: crafting, 1: furnace, 2: blast furnace, 3: smoker
			Book Open	Boolean
			Filter Active	Boolean

Update Jigsaw Block

Sent when Done is pressed on the Jigsaw Block interface.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x27 0x28	Play	Server	Location	Position	Block entity location
			Attachment type	Identifier
			Name	Identifier
			Target	Identifier
			Target pool Pool	Identifier
			Final state	String	"Turns into" on the GUI, final_state in NBT
			Joint type	String	rollable if the attached piece can be rotated, else aligned

Entity Equipment

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x47	Play	Client	Entity ID		VarInt		Entity's EID
			Slot		VarInt Enum		Equipment slot. 0: main hand, 1: off hand, 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet)
			Item		Slot
			Equipment	Slot	Array	Byte Enum	Equipment slot. 0: main hand, 1: off hand, 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet). Also has the top bit set if another entry follows, and otherwise unset if this is the last item in the array.
				Item		Slot

Handshaking

Clientbound

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

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 578 741)
			Server Address	String	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 complete redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide mc.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

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	String (36) UUID	Unlike in other packets, this field contains the UUID as a string with hyphens.
			Username	String (16)

This packet switches the connection state to play.

Serverbound

No changes so far.