Pre-release protocol

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This page documents the changes from the last stable Minecraft release (currently 1.12.2, protocol 340) to the current pre-release (currently 18w33a, protocol 398). 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

Contents

Data types

Other definitions

Global palette

A table/dictionary/palette mapping nonnegative integers to block states. The block state IDs can be constructed from this table by multiplying what the Minecraft Wiki calls “block IDs” by 16 and adding the metadata/damage value (or in most programming languages block_id << 4 | metadata). Block state IDs are created in a linear fashion based off of order of assignment. One block state ID allocated for each unique block state for a block; if a block has multiple properties then the number of allocated states is the product of the number of values for each property. A current list of properties and state ID ranges is found on burger.

Alternatively, the vanilla server now includes an option to export the current block state ID mapping, by running java -cp minecraft_server.jar net.minecraft.data.Main --reports. See Data Generators for more information.

Packets

ID Packet name Documentation
Handshaking serverbound
0x00 Handshake Current Pre
Play clientbound
0x04 Spawn Painting Current Pre
0x07 Statistics Current Pre
0x09 Update Block Entity Current Pre
0x0B Block Change Current Pre
0x0C Boss Bar Current Pre
0x0F 0x0E Chat Message (clientbound) Current (unchanged)
0x10 0x0F Multi Block Change Current Pre
0x0E 0x10 Tab-Complete (clientbound) Current Pre
0x11 Declare Commands Pre
0x11 0x12 Confirm Transaction (clientbound) Current (unchanged)
0x12 0x13 Close Window (clientbound) Current (unchanged)
0x13 0x14 Open Window Current (unchanged)
0x14 0x15 Window Items Current (unchanged)
0x15 0x16 Window Property Current (unchanged)
0x16 0x17 Set Slot Current (unchanged)
0x17 0x18 Set Cooldown Current (unchanged)
0x18 0x19 Plugin Message (clientbound) Current Pre
0x19 0x1A Named Sound Effect Current Pre
0x1A 0x1B Disconnect (play) Current (unchanged)
0x1B 0x1C Entity Status Current (unchanged)
0x1D NBT Query Response Pre
0x1C 0x1E Explosion Current (unchanged)
0x1D 0x1F Unload Chunk Current (unchanged)
0x1E 0x20 Change Game State Current (unchanged)
0x1F 0x21 Keep Alive (clientbound) Current (unchanged)
0x20 0x22 Chunk Data Current Pre
0x21 0x23 Effect Current Pre
0x22 0x24 Spawn Particle Current Pre
0x23 0x25 Join Game Current (unchanged)
0x24 0x26 Map Current Pre
0x25 0x27 Entity Current (unchanged)
0x26 0x28 Entity Relative Move Current (unchanged)
0x27 0x29 Entity Look And Relative Move Current (unchanged)
0x28 0x2A Entity Look Current (unchanged)
0x29 0x2B Vehicle Move (clientbound) Current (unchanged)
0x2A 0x2C Open Sign Editor Current (unchanged)
0x2B 0x2D Craft Recipe Response Current Pre
0x2C 0x2E Player Abilities (clientbound) Current (unchanged)
0x2D 0x2F Combat Event Current (unchanged)
0x2E 0x30 Player List Item Current (unchanged)
0x31 Face Player Pre
0x2F 0x32 Player Position And Look (clientbound) Current (unchanged)
0x30 0x33 Use Bed Current (unchanged)
0x31 0x34 Unlock Recipes Current Pre
0x32 0x35 Destroy Entities Current (unchanged)
0x33 0x36 Remove Entity Effect Current (unchanged)
0x34 0x37 Resource Pack Send Current (unchanged)
0x35 0x38 Respawn Current (unchanged)
0x36 0x39 Entity Head Look Current (unchanged)
0x37 0x3A Select Advancement Tab Current (unchanged)
0x38 0x3B World Border Current (unchanged)
0x39 0x3C Camera Current (unchanged)
0x3A 0x3D Held Item Change (clientbound) Current (unchanged)
0x3B 0x3E Display Scoreboard Current (unchanged)
0x3C 0x3F Entity Metadata Current (unchanged)
0x3D 0x40 Attach Entity Current (unchanged)
0x3E 0x41 Entity Velocity Current (unchanged)
0x3F 0x42 Entity Equipment Current (unchanged)
0x40 0x43 Set Experience Current (unchanged)
0x41 0x44 Update Health Current (unchanged)
0x42 0x45 Scoreboard Objective Current Pre
0x43 0x46 Set Passengers Current (unchanged)
0x44 0x47 Teams Current Pre
0x45 0x48 Update Score Current (unchanged)
0x46 0x49 Spawn Position Current (unchanged)
0x47 0x4A Time Update Current (unchanged)
0x48 0x4B Title Current (unchanged)
0x4C Stop Sound Pre
0x49 0x4D Sound Effect Current (unchanged)
0x4A 0x4E Player List Header And Footer Current (unchanged)
0x4B 0x4F Collect Item Current (unchanged)
0x4C 0x50 Entity Teleport Current (unchanged)
0x4D 0x51 Advancements Current (unchanged)
0x4E 0x52 Entity Properties Current (unchanged)
0x4F 0x53 Entity Effect Current (unchanged)
0x54 Declare Recipes Pre
0x55 Tags Pre
Play serverbound
0x01 Query Block NBT Pre
0x01 0x05 Tab-Complete (serverbound) Current Pre
0x05 0x06 Confirm Transaction (serverbound) Current (unchanged)
0x06 0x07 Enchant Item Current (unchanged)
0x07 0x08 Click Window Current (unchanged)
0x08 0x09 Close Window (serverbound) Current (unchanged)
0x09 0x0A Plugin message (serverbound) Current Pre
0x0B Edit Book Pre
0x0C Query Entity NBT Pre
0x0A 0x0D Use Entity Current (unchanged)
0x0B 0x0E Keep Alive (serverbound) Current (unchanged)
0x0C 0x0F Player Current (unchanged)
0x0D 0x10 Player Position Current (unchanged)
0x0E 0x11 Player Position And Look (serverbound) Current (unchanged)
0x0F 0x12 Player Look Current (unchanged)
0x10 0x13 Vehicle Move (serverbound) Current (unchanged)
0x11 0x14 Steer Boat Current (unchanged)
0x15 Pick Item Pre
0x12 0x16 Craft Recipe Request Current Pre
0x13 0x17 Player Abilities (serverbound) Current (unchanged)
0x14 0x18 Player Digging Current (unchanged)
0x15 0x19 Entity Action Current (unchanged)
0x16 0x1A Steer Vehicle Current (unchanged)
0x17 0x1B Recipe Book Data Current Pre
0x1C Name Item Pre
0x18 0x1D Resource Pack Status Current (unchanged)
0x19 0x1E Advancement Tab Current (unchanged)
0x1F Select Trade Pre
0x20 Set Beacon Effect Pre
0x1A 0x21 Held Item Change (serverbound) Current (unchanged)
0x22 Update Command Block Pre
0x23 Update Command Block Minecart Pre
0x1B 0x24 Creative Inventory Action Current (unchanged)
0x25 Update Structure Block Pre
0x1C 0x26 Update Sign Current (unchanged)
0x1D 0x27 Animation (serverbound) Current (unchanged)
0x1E 0x28 Spectate Current (unchanged)
0x1F 0x29 Player Block Placement Current (unchanged)
0x20 0x2A Use Item Current (unchanged)
Login clientbound
0x04 Login Plugin Request Pre
Login serverbound
0x02 Login Plugin Response Pre

New/modified data types

Slot

Name Type Meaning
Block ID Item ID Short The item/block ID. A value of -1 signifies that the slot is empty, and no further data follows. Item IDs are now uniquely defined and are completely independent of block IDs.
Item Count Optional Byte Not present if Block ID is -1.
Item Damage Optional Short Not present if Block ID is -1.
NBT Optional NBT Not present if Block ID is -1. If 0, there is no NBT data, and no further data follows. Otherwise the byte is the start of an NBT blob as shown below:

Particle

Field Name Field Type Meaning
ID VarInt The ID of the particle type, see below.
Data Varies Varies based on the particle type, see below.
Particle Name Particle ID Data
minecraft:ambient_entity_effect 0 None
minecraft:angry_villager 1 None
minecraft:barrier 2 None
minecraft:block 3
Field Name Field Type Meaning
BlockState VarInt The ID of the block state.
minecraft:bubble 4 None
minecraft:cloud 5 None
minecraft:crit 6 None
minecraft:damage_indicator 7 None
minecraft:dragon_breath 8 None
minecraft:dripping_lava 9 None
minecraft:dripping_water 10 None
minecraft:dust 11
Field Name Field Type Meaning
Red Float Red value, 0-1
Green Float Green value, 0-1
Blue Float Blue value, 0-1
Scale Float The scale, will be clamped between 0.01 and 4.
minecraft:effect 12 None
minecraft:elder_guardian 13 None
minecraft:enchanted_hit 14 None
minecraft:enchant 15 None
minecraft:end_rod 16 None
minecraft:entity_effect 17 None
minecraft:explosion_emitter 18 None
minecraft:explosion 19 None
minecraft:falling_dust 20
Field Name Field Type Meaning
BlockState VarInt The ID of the block state.
minecraft:firework 21 None
minecraft:fishing 22 None
minecraft:flame 23 None
minecraft:happy_villager 24 None
minecraft:heart 25 None
minecraft:instant_effect 26 None
minecraft:item 27
Field Name Field Type Meaning
Item Slot The item that will be used.
minecraft:item_slime 28 None
minecraft:item_snowball 29 None
minecraft:large_smoke 30 None
minecraft:lava 31 None
minecraft:mycelium 32 None
minecraft:note 33 None
minecraft:poof 34 None
minecraft:portal 35 None
minecraft:rain 36 None
minecraft:smoke 37 None
minecraft:spit 38 None
minecraft:squid_ink 39 None
minecraft:sweep_attack 40 None
minecraft:totem_of_undying 41 None
minecraft:underwater 42 None
minecraft:splash 43 None
minecraft:witch 44 None
minecraft:bubble_pop 45 None
minecraft:current_down 46 None
minecraft:bubble_column_up 47 None
minecraft:nautilus 48 None
minecraft:dolphin 49 None

Chat

Selector component

Displays the results of an entity selector. Should not be sent to clients; only intended for commands and client-to-server actions. If the component contains a selector key, then it is a selector component.

The server resolves the list selector into a list of entities, each with an appropriate hover event, and joined with commas and "and" (but it lacks a serial comma) joined with commas between each entry, without an "and".

Entity Metadata Format

Note that entity metadata is a totally distinct concept from block metadata. It is not required to send all metadata fields, or even any metadata fields, so long as the terminating entry is correctly sent.

Entity Metadata is an array of entries, each of which looks like the following:

Name Type Meaning
Index Unsigned Byte Unique index key determining the meaning of the following value, see the table below. If this is 0xff then the it is the end of the Entity Metadata array and no more is read.
Type Optional Byte Enum Only if Index is not 0xff; the type of the index, see the table below
Value Optional value of Type Only if Index is not 0xff: the value of the metadata field
Value of Type field Type of Value field Notes
0 Byte
1 VarInt
2 Float
3 String
4 Chat
5 OptChat (Boolean + Optional Chat) Chat is present if the Boolean is set to true
5 6 Slot
6 7 Boolean
7 8 Rotation 3 floats: rotation on x, rotation on y, rotation on z
8 9 Position
9 10 OptPosition (Boolean + Optional Position) Position is present if the Boolean is set to true
10 11 Direction (VarInt) (Down = 0, Up = 1, North = 2, South = 3, West = 4, East = 5)
11 12 OptUUID (Boolean + Optional UUID) UUID is present if the Boolean is set to true
12 13 OptBlockID (VarInt) 0 for absent, otherwise index into the global palette. (Air is treated as absent)
13 14 NBT Tag
15 #Particle

Entity

The base class.

Index Type Meaning Default
0 Byte Bit mask Meaning 0
0x01 On Fire
0x02 Crouched
0x04 Unused (previously riding)
0x08 Sprinting
0x10 Unused (previously eating/drinking/blocking; use hand state now) Swimming
0x20 Invisible
0x40 Glowing effect
0x80 Flying with elytra
1 VarInt Air 300
2 String OptChat Custom name empty
3 Boolean Is custom name visible false
4 Boolean Is silent false
5 Boolean No gravity false

AreaEffectCloud

Extends Entity.

Index Type Meaning Default
6 Float Radius 0.5
7 VarInt Color (only for mob spell particle) 0
8 Boolean Ignore radius and show effect as single point, not area false
9 Particle The #Particle effect
9 VarInt Particle ID 15 (mobSpell)
10 VarInt Particle parameter 1 0
11 VarInt Particle parameter 2 0

Arrow

Extends Entity.

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

Index Type Meaning Default
6 Byte Bit mask Meaning 0
0x01 Is critical
7 OptUUID Shooter UUID Empty

TippedArrow

Extends 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
7 8 VarInt Color (-1 for no particles) -1

Trident

Extends Arrow.

Index Type Meaning Default
8 VarInt Loyalty level (enchantment) 0

Boat

Extends Entity.

Index Type Meaning Default
6 VarInt Time since last hit 0
7 VarInt Forward direction 1
8 Float Damage taken 0.0
9 VarInt Type (0=oak, 1=spruce, 2=birch, 3=jungle, 4=acacia, 5=dark oak) 0
10 Boolean Right paddle turning false
11 Boolean Left paddle turning false
12 VarInt Splash timer (?) 0

Phantom

Extends Flying.

Index Type Meaning Default
12 VarInt Size 0

Hitbox size is determined by horizontal=0.9 + 0.2*size and vertical=0.5 + 0.1 * i

Dolphin

Extends Creature.

Index Type Meaning Default
12 Position Treasure position (0, 0, 0)
13 Boolean Can find treasure false
14 Boolean Has fish false

WaterMob

Extends Insentient Creature.

No additional metadata.

Abstract fish

Extends WaterMob.

Index Type Meaning Default
12 Boolean From bucket False

Cod

Extends AbstractFish.

No additional metadata.

Puffer fish

Extends AbstractFish.

Index Type Meaning Default
13 VarInt PuffState (varies from 0 to 2) 0

Salmon

Extends AbstractFish.

No additional metadata.

Tropical fish

Extends AbstractFish.

Index Type Meaning Default
13 VarInt Variant 0

Turtle

Extends Animal.

Index Type Meaning Default
13 BlockPos Home pos (0, 0, 0)
14 Boolean Has egg false
15 Boolean Laying egg (?) false
16 BlockPos Travel pos (0, 0, 0)
17 Boolean Going home false
18 Boolean Traveling false

Zombie

Extends Monster.

Index Type Meaning Default
12 Boolean Is baby false
13 VarInt Unused (previously type) 0
14 Boolean Are hands held up false
15 Boolean Is becoming a drowned false

Drowned

Extends Zombie.

No additional metadata.

Block Actions

Note Block

Displays a colored note particle and plays the appropriate note sound effect.

In 1.13, the parameters are no longer used to determine what effect to use; instead, the information is obtained from the block state.

Action IDs

The action ID is used to determine the instrument to play. Ignored, always 0.

Type ID Instrument Material/block Sound
0 Harp Any other material block.note.harp
1 Bass Drum Stone block.note.harp
2 Snare Drum Sand block.note.snare
3 Clicks/Sticks Glass block.note.hat
4 Bass guitar Wood block.note.bass
5 Flute Clay block.note.flute
6 Bell Gold block block.note.bell
7 Guitar Wool block.note.guitar
8 Chime Packed ice block.note.chime
9 Xylophone Bone block block.note.xylophone

Any unknown ID is treated as if it were 0.

The sound event block.note.pling is unassigned and unused.

Action param

The pitch of the note (between 0–24 inclusive where 0 is the lowest and 24 is the highest). Ignored, always 0. More information about how the pitch values correspond to notes in real life and how they correspond to pitch scaling on the sound effects can be found in the Note Block article on the Minecraft wiki.

Plugin Channels

All clientbound channels have been renamed to be namespaced identifiers.

minecraft:register

Formerly REGISTER.

minecraft:unregister

Formerly UNREGISTER.

minecraft:brand

Formerly MC|Brand.

minecraft:book_open

Formerly MC|BOpen.

minecraft:trader_list

Formerly MC|TrList.

MC|StopSound

Server to client

Used to implement the /stopsound command. Stops a sound that is currently playing on the client.

Field name Field type Notes
Sound category String Should be one of the sound categories used in Named Sound Effect, but if it's invalid or empty then it is (intentionally) treated as all sound categories.
Sound name String A sound effect name. If left empty, all sounds are stopped.

Emptiness of sound category or sound name can be combined, IE a empty sound name but a set sound category will stop all sounds in the given category.

This plugin channel has been replaced by the stop sound packet.

minecraft:debug/paths

Formerly MC|DebugPath.

minecraft:debug/neighbors_update

Formerly MC|DebugNeighborsUpdate.

minecraft:debug/caves

Never sent, but (presumably) used to debug caves. Does not render without modifying the client.

Field name Field type Notes
Unknown 1 Position
Count Int Number of elements in the following array
Data Unknown 2 Array Position
Unknown 3 Float

minecraft:debug/structures

Never sent, but (presumably) used to debug structures. Does not render without modifying the client.

Field name Field type Notes
Unknown 1 Int
Bounding box minX Int min must be less than max
Bounding box minY Int
Bounding box minZ Int
Bounding box maxX Int
Bounding box maxY Int
Bounding box maxZ Int
Count Int Number of elements in the following array
Unknown Bounding box minX Array Int min must be less than max
Bounding box minY Int
Bounding box minZ Int
Bounding box maxX Int
Bounding box maxY Int
Bounding box maxZ Int
Unknown Boolean

minecraft:debug/worldgen_attempt

Never sent, but (presumably) used to debug something with world generation. Does not render without modifying the client.

Warning.png This channel is invalid, as its name is longer than the max length (23 > 20).

Field name Field type Notes
Unknown 1 Position
Unknown 2 Float
Unknown 3 Float
Unknown 4 Float
Unknown 5 Float
Unknown 6 Float

MC|BEdit

Client to server Removed and replaced with Edit Book.

MC|BSign

Client to server Removed and replaced with Edit Book.

MC|TrSel

Client to server Removed and replaced with Select Trade.

MC|AdvCmd

Client to server Removed and replaced with Update Command Block Minecart (legacy usage may also require Update Command Block).

MC|AutoCmd

Client to server Removed and replaced with Update Command Block.

MC|Beacon

Client to server Removed and replaced with Set Beacon Effect.

MC|ItemName

Client to server Removed and replaced with Name Item.

MC|Struct

Client to server Removed and replaced with Update Structure Block.

MC|PickItem

Client to server Removed and replaced with Pick Item.

Community plugin channels

BungeeCord

Renamed to bungeecord:main.

WDL|INIT, WDL|CONTROL, WDL|REQUEST

Renamed to wdl:init, wdl:control, and wdl:request respectively.

Play

Clientbound

Spawn Painting

This packet shows location, name, and type of painting.

Packet ID State Bound To Field Name Field Type Notes
0x04 Play Client Entity ID VarInt
Entity UUID UUID
Motive String (13) VarInt Name of the painting. Max length 13 Panting's ID, see below
Location Position Center coordinates (see below)
Direction Byte Enum Direction the painting faces (North = 2, South = 0, West = 1, East = 3)

Calculating the center of an image: given a (width × height) grid of cells, with (0, 0) being the top left corner, the center is (max(0, width / 2 - 1), height / 2). E.g. (1, 0) for a 2×1 painting, or (1, 2) for a 4×4 painting.

List of paintings by coordinates in paintings_kristoffer_zetterstrand.png (where x and y are in pixels from the top left and width and height are in pixels or 16ths of a block):

Name ID x y width height
Kebab minecraft:kebab 0 0 0 16 16
Aztec minecraft:aztec 1 16 0 16 16
Alban minecraft:alban 2 32 0 16 16
Aztec2 minecraft:aztec2 3 48 0 16 16
Bomb minecraft:bomb 4 64 0 16 16
Plant minecraft:plant 5 80 0 16 16
Wasteland minecraft:wasteland 6 96 0 16 16
Pool minecraft:pool 7 0 32 32 16
Courbet minecraft:courbet 8 32 32 32 16
Sea minecraft:sea 9 64 32 32 16
Sunset minecraft:sunset 10 96 32 32 16
Creebet minecraft:creebet 11 128 32 32 16
Wanderer minecraft:wanderer 12 0 64 16 32
Graham minecraft:graham 13 16 64 16 32
Match minecraft:match 14 0 128 32 32
Bust minecraft:bust 15 32 128 32 32
Stage minecraft:stage 16 64 128 32 32
Void minecraft:void 17 96 128 32 32
SkullAndRoses skull_and_roses 18 128 128 32 32
Wither minecraft:wither 19 160 128 32 32
Fighters minecraft:fighters 20 0 96 64 32
Pointer minecraft:pointer 21 0 192 64 64
Pigscene minecraft:pigscene 22 64 192 64 64
BurningSkull minecraft:burning_skull 23 128 192 64 64
Skeleton minecraft:skeleton 24 192 64 64 48
DonkeyKong minecraft:donkey_kong 25 192 112 64 48

The Minecraft Wiki article on paintings also provides a list of painting names to the actual images.

Statistics

Sent as a response to Client Status (id 1).

Packet ID State Bound To Field Name Field Type Notes
0x07 Play Client Count VarInt Number of elements in the following array
Statistic Name Array String (32767) https://gist.github.com/Alvin-LB/8d0d13db00b3c00fd0e822a562025eff
Category ID VarInt See below
Statistic ID VarInt See below
Value VarInt The amount to set it to

Categories (these are namespaced, but with :. replaced with .):

Name ID Registry
minecraft.mined 0 Blocks
minecraft.crafted 1 Items
minecraft.used 2 Items
minecraft.broken 3 Items
minecraft.picked_up 4 Items
minecraft.dropped 5 Items
minecraft.killed 6 Entities
minecraft.killed_by 7 Entities
minecraft.custom 8 Custom

Blocks, Items, and Entities use block (not block state), item, and entity ids.

Custom has the following (unit only matters for clients):

Name ID Unit
minecraft.leave_game 0 None
minecraft.play_one_minute 1 Time
minecraft.time_since_death 2 Time
minecraft.sneak_Time 3 Time
minecraft.walk_one_cm 4 Distance
minecraft.crouch_one_cm 5 Distance
minecraft.sprint_one_cm 6 Distance
minecraft.swim_one_cm 7 Distance
minecraft.fall_one_cm 8 Distance
minecraft.climb_one_cm 9 Distance
minecraft.fly_one_cm 10 Distance
minecraft.dive_one_cm 11 Distance
minecraft.minecart_one_cm 12 Distance
minecraft.boat_one_cm 13 Distance
minecraft.pig_one_cm 14 Distance
minecraft.horse_one_cm 15 Distance
minecraft.aviate_one_cm 16 Distance
minecraft.jump 17 None
minecraft.drop 18 None
minecraft.damage_dealt 19 Damage
minecraft.damage_taken 20 Damage
minecraft.deaths 21 None
minecraft.mob_kills 22 None
minecraft.animals_bred 23 None
minecraft.player_kills 24 None
minecraft.fish_caught 25 None
minecraft.talked_to_villager 26 None
minecraft.traded_with_villager 27 None
minecraft.eat_cake_slice 28 None
minecraft.fill_cauldron 29 None
minecraft.use_cauldron 30 None
minecraft.clean_armor 31 None
minecraft.clean_banner 32 None
minecraft.interact_with_brewingstand 33 None
minecraft.interact_with_beacon 34 None
minecraft.inspect_dropper 35 None
minecraft.inspect_hopper 36 None
minecraft.inspect_dispenser 37 None
minecraft.play_noteblock 38 None
minecraft.tune_noteblock 39 None
minecraft.pot_flower 40 None
minecraft.trigger_trapped_chest 41 None
minecraft.open_enderchest 42 None
minecraft.enchant_item 43 None
minecraft.play_record 44 None
minecraft.interact_with_furnace 45 None
minecraft.interact_with_crafting_table 46 None
minecraft.open_chest 47 None
minecraft.sleep_in_bed 48 None
minecraft.open_shulker_box 49 None

Units:

  • None: just a normal number (formatted with 0 decimal places)
  • Damage: value is 10 times the normal amount
  • Distance: a distance in centimeters (hundredths of blocks)
  • Time: a time span in ticks

Update Block Entity

Sets tile entity associated with the block at the given location.

Packet ID State Bound To Field Name Field Type Notes
0x09 Play Client Location Position
Action Unsigned Byte The type of update to perform, see below
NBT Data NBT Tag Data to set. May be a TAG_END (0), in which case the block entity at the given location is removed (though this is not required since the client will remove the block entity automatically on chunk unload or block removal)

Action field:

  • 1: Set data of a mob spawner (everything except for SpawnPotentials: current delay, min/max delay, mob to be spawned, spawn count, spawn range, etc.)
  • 2: Set command block text (command and last execution status)
  • 3: Set the level, primary, and secondary powers of a beacon
  • 4: Set rotation and skin of mob head
  • 5: Set type of flower in flower pot
  • 5: Declare a conduit
  • 6: Set base color and patterns on a banner
  • 7: Set the data for a Structure tile entity
  • 8: Set the destination for a end gateway
  • 9: Set the text on a sign
  • 10: Declare a shulker box, no data appears to be sent and the client seems to do fine without this packet. Perhaps it is a leftover from earlier versions?
  • 11: Set the color of a bed Declare a bed

Block Change

Fired whenever a block is changed within the render distance.

Warning.png Changing a block in a chunk that is not loaded is not a stable action. The Notchian client currently uses a shared empty chunk which is modified for all block changes in unloaded chunks; while in 1.9 this chunk never renders in older versions the changed block will appear in all copies of the empty chunk. Servers should avoid sending block changes in unloaded chunks and clients should ignore such packets.

Packet ID State Bound To Field Name Field Type Notes
0x0B Play Client Location Position Block Coordinates
Block ID VarInt The new block state ID for the block as given in the global palette. (When reading data: type = id >> 4, meta = id & 15, when writing data: id = type << 4 | (meta & 15)) See that section for more information.

Boss Bar

Packet ID State Bound To Field Name Field Type Notes
0x0C Play Client UUID UUID Unique ID for this bar
Action VarInt Enum Determines the layout of the remaining packet
Action Field Name
0: add Title Chat
Health Float From 0 to 1. Values greater than 1 do not crash a Notchian client, and start rendering part of a second health bar at around 1.5.
Color VarInt Enum Color ID (see below)
Division VarInt Enum Type of division (see below)
Flags Unsigned Byte Bit mask. 0x1: should darken sky, 0x2: is dragon bar (used to play end music), 0x04: create fog (previously was also controlled by 0x02)
1: remove no fields no fields Removes this boss bar
2: update health Health Float as above
3: update title Title Chat
4: update style Color VarInt Enum Color ID (see below)
Dividers VarInt Enum as above
5: update flags Flags Unsigned Byte as above
ID Color
0 Pink
1 Blue
2 Red
3 Green
4 Yellow
5 Purple
6 White
ID Type of division
0 No division
1 6 notches
2 10 notches
3 12 notches
4 20 notches

Multi Block Change

Fired whenever 2 or more blocks are changed within the same chunk on the same tick.

Warning.png Changing blocks in chunks not loaded by the client is unsafe (see note on Block Change).

Packet ID State Bound To Field Name Field Type Notes
0x10 0x0F Play Client Chunk X Int Chunk X coordinate
Chunk Z Int Chunk Z coordinate
Record Count VarInt Number of elements in the following array, i.e. the number of blocks affected
Record Horizontal Position Array Unsigned Byte The 4 most significant bits (0xF0) encode the X coordinate, relative to the chunk. The 4 least significant bits (0x0F) encode the Z coordinate, relative to the chunk.
Y Coordinate Unsigned Byte Y coordinate of the block
Block ID VarInt The new block state ID for the block as given in the global palette. (When reading data: type = id >> 4, meta = id & 15, when writing data: id = type << 4 | (meta & 15)) See that section for more information.

To decode the position into a world position:

worldX = (horizPos >> 4 & 15) + (chunkX * 16);
worldY = vertPos;
worldZ = (horizPos & 15) + (chunkZ * 16);


Tab-Complete (clientbound)

Used to respond to the client's previous tab complete request.

Packet ID State Bound To Field Name Field Type Notes
0x0E 0x10 Play Client Transaction Id VarInt This id should also be used in the tab completion response packet, or it will be ignored.
Start VarInt Start of the text to replace
Length VarInt Length of the text to replace
Count VarInt Number of elements in the following array
Matches Match Array String (32767) One eligible command value to insert, note that each command is sent separately instead of in a single string, hence the need for Count. Note that for instance this doesn't include a leading / on commands.
Has tooltip Boolean True if the following is present
Tooltip Optional Chat Tooltip to display; only present if previous Boolean is true

Declare Commands

Lists all of the commands on the server, and how they are parsed.

This is a directed graph, with one root node. Each redirect or child node must refer only to nodes that have already been declared.

Packet ID State Bound To Field Name Field Type Notes
0x11 Play Client Count VarInt Number of elements in the following array
Nodes Array of Node An array of nodes
Root index VarInt Index of the root node in the previous array

For more information on this packet, see the Command Data article.

Plugin Message (clientbound)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses a number of plugin channels. These internal channels are prefixed with MC|.

More documentation on this: http://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Packet ID State Bound To Field Name Field Type Notes
0x18 0x19 Play Client Channel String (20) Identifier Name of the plugin channel used to send the data
Data Byte Array Any data, depending on the channel. MC| channels are documented here. The length of this array must be inferred from the packet length.


Named Sound Effect

See also: #Sound Effect

Used to play a sound effect on the client. Custom sounds may be added by resource packs.

Packet ID State Bound To Field Name Field Type Notes
0x19 0x1A Play Client Sound Name String (256) Identifier All sound effect names as of 1.13-pre8 can be seen here.
Sound Category VarInt Enum The category that this sound will be played from (current categories)
Effect Position X Int Effect X multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part)
Effect Position Y Int Effect Y multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part)
Effect Position Z Int Effect Z multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part)
Volume Float 1 is 100%, can be more
Pitch Float Float between 0.5 and 2.0 by Notchian clients

NBT Query Response

Sent in response to Query Block NBT or Query Entity NBT.

Packet ID State Bound To Field Name Field Type Notes
0x1D Play Client Transaction ID VarInt Can be compared to the one sent in the original query packet.
NBT NBT Tag The NBT of the block or entity. May be a TAG_END (0) in which case no NBT is present.

Chunk Data

Main article: Chunk Format
See also: #Unload Chunk

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).

Indexes into the global palette are still used, but since the global palette has changed, behavior is different. The Palette length field is no longer sent when using the global palette

The bits per block value used to index in the global palette is 13 14, which is determined by taking the base 2 logarithm of the highest state ID and then rounding up (or alternatively, simply checking how many bits are needed to represent the highest state ID).

Packet ID State Bound To Field Name Field Type Notes
0x20 0x22 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)
Ground-Up Continuous Boolean See Chunk Format
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).
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.

Warning.png The chunk data packet currently (for 1.13 snapshots) may allocate a data array slightly larger than necessary; see MC-131684. As such, there may be extra data (all zeros) after the end of the buffer that is not used.

Data structure

The data section of the packet contains most of the useful data for the chunk.

Field Name Field Type Notes
Data Array of Chunk Section The number of elements is equal to the number of bits set in Primary Bit Mask. Sections are sent bottom-to-top, i.e. the first section, if sent, extends from Y=0 to Y=15.
Biomes Optional Byte Int Array Only sent if Ground-Up Continuous is true; 256 bytes entries if present
Direct palette

This format is used for bits per block values greater than or equal to 9. The number of bits used to represent a block are the base 2 logarithm of the number of block states, rounded up. For the current vanilla release, this is 13 bits per block.

The "palette" uses the following format:
Field Name Field Type Notes
Dummy Palette Length VarInt Should always be 0. Only exists to mirror the format used elsewhere.
no fields

If Minecraft Forge is installed and a sufficiently large number of blocks are added, the bits per block value for the global palette will be increased to compensate for the increased ID count. This increase can go up to 16 bits per block (for a total of 4096 block IDs; when combined with the 16 damage values, there are 65536 total states). You can get the number of blocks with the "Number of ids" field found in the RegistryData packet in the Forge Handshake.

Effect

Sent when a client is to play a sound or particle effect.

By default, the Minecraft client adjusts the volume of sound effects based on distance. The final boolean field is used to disable this, and instead the effect is played from 2 blocks away in the correct direction. Currently this is only used for effect 1023 (wither spawn) and effect 1028 (enderdragon death); it is ignored on other effects.

Packet ID State Bound To Field Name Field Type Notes
0x21 0x23 Play Client Effect ID Int The ID of the effect, see below
Location Position The location of the effect
Data Int Extra data for certain effects, see below
Disable Relative Volume Boolean See above

Effect IDs:

ID Name Data
Sound
1000 Dispenser dispenses
1001 Dispenser fails to dispense
1002 Dispenser shoots
1003 Ender eye launched
1004 Firework shot
1005 Iron door opened
1006 Wooden door opened
1007 Wooden trapdoor opened
1008 Fence gate opened
1009 Fire extinguished
1010 Play record Special case, see below for more info
1011 Iron door closed
1012 Wooden door closed
1013 Wooden trapdoor closed
1014 Fence gate closed
1015 Ghast warns
1016 Ghast shoots
1017 Enderdragon shoots
1018 Blaze shoots
1019 Zombie attacks wood door
1020 Zombie attacks iron door
1021 Zombie breaks wood door
1022 Wither breaks block
1023 Wither spawned
1024 Wither shoots
1025 Bat takes off
1026 Zombie infects
1027 Zombie villager converted
1028 Ender dragon death
1029 Anvil destroyed
1030 Anvil used
1031 Anvil landed
1032 Portal travel
1033 Chorus flower grown
1034 Chorus flower died
1035 Brewing stand brewed
1036 Iron trapdoor opened
1037 Iron trapdoor closed
Particle
2000 Spawns 10 smoke particles, e.g. from a fire Direction, see below
2001 Block break + block break sound Block state, determined by meta << 12 | block id (this differs from normal global palette use) as an index into the global palette
2002 Splash potion. Particle effect + glass break sound. Potion ID
2003 Eye of Ender entity break animation — particles and sound
2004 Mob spawn particle effect: smoke + flames
2005 Bonemeal particles How many particles to spawn (if set to 0, 15 are spawned)
2006 Dragon breath
2007 Instant splash potion Potion ID
3000 End gateway spawn
3001 Enderdragon growl

Smoke directions:

ID Direction
0 South-East
1 South
2 South-West
3 East
4 (Up or middle ?)
5 West
6 North-East
7 North
8 North-West

Play record: This is actually a special case within this packet. You can start/stop a record at a specific location. Use a valid Record ID to start a record (or overwrite a currently playing one), any other value will stop the record. While this packet still uses item IDs, item IDs have changed in 1.13.

Spawn Particle

Displays the named particle

Packet ID State Bound To Field Name Field Type Notes
0x22 0x24 Play Client Particle ID Int The particle ID listed in #Particle.
Long Distance Boolean If true, particle distance increases from 256 to 65536
X Float X position of the particle
Y Float Y position of the particle
Z Float Z position of the particle
Offset X Float This is added to the X position after being multiplied by random.nextGaussian()
Offset Y Float This is added to the Y position after being multiplied by random.nextGaussian()
Offset Z Float This is added to the Z position after being multiplied by random.nextGaussian()
Particle Data Float The data of each particle
Particle Count Int The number of particles to create
Data Array of VarInt Varies Length depends on particle. "iconcrack" has length of 2, "blockcrack", "blockdust", and "fallingdust" have lengths of 1, the rest have 0. The variable data listed in #Particle

Map

Updates a rectangular area on a map item.

Packet ID State Bound To Field Name Field Type Notes
0x24 0x26 Play Client Item Damage VarInt The damage value (map ID) of the map being modified
Scale Byte From 0 for a fully zoomed-in map (1 block per pixel) to 4 for a fully zoomed-out map (16 blocks per pixel)
Tracking Position Boolean Specifies whether the icons are shown
Icon Count VarInt Number of elements in the following array
Icon Direction And Type Type Array Byte VarInt enum 0xF0 = Type, 0x0F = Direction Type (see below)
X Byte
Z Byte
Direction Byte 0-15
Has Display Name Boolean
Display Name Optional Chat Only present if previous Boolean is true
Columns Byte Number of columns updated
Rows Optional Byte Only if Columns is more than 0; number of rows updated
X Optional Byte Only if Columns is more than 0; x offset of the westernmost column
Z Optional Byte Only if Columns is more than 0; z offset of the northernmost row
Length Optional VarInt Only if Columns is more than 0; length of the following array
Data Optional Array of Unsigned Byte Only if Columns is more than 0; see Map item format

For icons, a direction of 0 is a vertical icon and increments by 22.5° (360/16).

Types are based off of rows and columns in map_icons.png:

Icon type Result
0 White arrow (players)
1 Green arrow (item frames)
2 Red arrow
3 Blue arrow
4 White cross
5 Red pointer
6 White circle (off-map players)
7 Small white circle (far-off-map players)
8 Mansion
9 Temple
10 White Banner
11 Orange Banner
12 Magenta Banner
13 Light Blue Banner
14 Yellow Banner
15 Lime Banner
16 Pink Banner
17 Gray Banner
18 Light Gray Banner
19 Cyan Banner
20 Purple Banner
21 Blue Banner
22 Brown Banner
23 Green Banner
24 Red Banner
25 Black Banner
26 Treasure marker

Craft Recipe Response

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

Packet ID State Bound To Field Name Field Type Notes
0x2B 0x2D Play Client Window ID Byte
Recipe VarInt Identifer A recipe ID

Face Player

Used to rotate the client player to face the given location or entity (for /teleport [<targets>] <x> <y> <z> facing).

Packet ID State Bound To Field Name Field Type Notes
0x31 Play Client
Feet/eyes VarInt enum Values are feet=0, eyes=1. If set to eyes, aims using the head position; otherwise aims using the feet position.
Target x Double x coordinate of the point to face towards
Target y Double y coordinate of the point to face towards
Target z Double z coordinate of the point to face towards
Is entity Boolean If true, additional information about an entity is provided.
Entity ID Optional VarInt Only if is entity is true — the entity to face towards
Entity feet/eyes Optional VarInt enum Whether to look at the entity's eyes or feet. Same values and meanings as before, just for the entity's head/feet.

If the entity given by entity ID cannot be found, this packet should be treated as if is entity was false.

Unlock Recipes

Packet ID State Bound To Field Name Field Type Notes
0x31 0x34 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.
Array size 1 VarInt Number of elements in the following array
Recipe IDs Array of VarInt 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 VarInt 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.

Scoreboard Objective

This is sent to the client when it should create a new scoreboard objective or remove one.

Packet ID State Bound To Field Name Field Type Notes
0x42 0x45 Play Client Objective Name String (16) An unique name for the objective
Mode Byte 0 to create the scoreboard. 1 to remove the scoreboard. 2 to update the display text.
Objective Value Optional String (32) Chat Only if mode is 0 or 2. The text to be displayed for the score
Type Optional String VarInt Enum Only if mode is 0 or 2. “integer” or “hearts”

Teams

Creates and updates teams.

Packet ID State Bound To Field Name Field Type Notes
0x44 0x47 Play Client Team Name String (16) A unique name for the team. (Shared with scoreboard).
Mode Byte Determines the layout of the remaining packet
0: create team Team Display Name String (32) Chat
Team Prefix String (16) Displayed before the names of players that are part of this team
Team Suffix String (16) Displayed after the names of players that are part of this team
Friendly Flags Byte Bit mask. 0x01: Allow friendly fire, 0x02: can see invisible players on same team
Name Tag Visibility String Enum (32) always, hideForOtherTeams, hideForOwnTeam, never
Collision Rule String Enum (32) always, pushOtherTeams, pushOwnTeam, never
Color Formatting Byte VarInt enum For colors, the same Chat colors (0-15). -1 indicates RESET/no color. See below for more info.
Team Prefix Chat Displayed before the names of players that are part of this team
Team Suffix Chat Displayed after the names of players that are part of this team
Entity Count VarInt Number of elements in the following array
Entities Array of String (40) Identifiers for the entities in this team. For players, this is their username; for other entities, it is their UUID.
1: remove team no fields no fields
2: update team info Team Display Name String (32) Chat
Team Prefix String (16) Displayed before the names of entities that are part of this team
Team Suffix String (16) Displayed after the names of entities that are part of this team
Friendly Flags Byte Bit mask. 0x01: Allow friendly fire, 0x02: can see invisible entities on same team
Name Tag Visibility String Enum (32) always, hideForOtherTeams, hideForOwnTeam, never
Collision Rule String Enum (32) always, pushOtherTeams, pushOwnTeam, never
Color Formatting Byte VarInt enum For colors, the same Chat colors (0-15). -1 indicates RESET/no color. See below for more info.
Team Prefix Chat Displayed before the names of players that are part of this team
Team Suffix Chat Displayed after the names of players that are part of this team
3: add players to team Entity Count VarInt Number of elements in the following array
Entities Array of String (40) Identifiers for the entities added. For players, this is their username; for other entities, it is their UUID.
4: remove players from team Entity Count VarInt Number of elements in the following array
Entities Array of String (40) Identifiers for the entities removed. For players, this is their username; for other entities, it is their UUID.

Formatting: The formatting of a team defines how the names of the team members are visualized. The following table lists all the possible formattings.

ID Formatting
0-15 Color formatting, same values as Chat colors.
16 Obfuscated
17 Bold
18 Strikethrough
19 Underlined
20 Italic
21 Reset

Stop Sound

Packet ID State Bound To Field Name Field Type Notes
0x4C Play Client Flags Byte Controls which fields are present.
Source Optional VarInt enum Only if flags is 3 or 1 (bit mask 0x1). See below. If not present, then sounds from all sources are cleared.
Sound Optional Identifier Only if flags is 2 or 3 (bit mask 0x2). A sound effect name, see Named Sound Effect. If not present, then all sounds are cleared.

Categories:

Name Value
master 0
music 1
record 2
weather 3
block 4
hostile 5
neutral 6
player 7
ambient 8
voice 9

Declare Recipes

Packet ID State Bound To Field Name Field Type Notes
0x54 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 None
crafting_special_mapcloning Recipe for copying maps None
crafting_special_mapextending Recipe for adding paper to maps None
crafting_special_firework_rocket Recipe for making firework rockets None
crafting_special_firework_star Recipe for making firework stars None
crafting_special_firework_star_fade Recipe for making firework stars fade between multiple colors None
crafting_special_repairitem Recipe for repairing items via crafting None
crafting_special_tippedarrow Recipe for crafting tipped arrows None
crafting_special_bannerduplicate Recipe for copying banner patterns None
crafting_special_banneraddpattern Recipe for adding patterns to banners None
crafting_special_shielddecoration Recipe for applying a banner's pattern to a shield None
crafting_special_shulkerboxcoloring Recipe for recoloring a shulker box None
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

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.

Tags

Packet ID State Bound To Field Name Field Type Notes
0x55 Play Client Block Tags (See below) IDs are block IDs
Item Tags (See below) IDs are item IDs
Fluid Tags (See below) IDs are fluid IDs

Tags look like:

Field Name Field Type Notes
Length VarInt Number of elements in the following array
Tags Tag name Array Identifier
Count VarInt Number of elements in the following array
Entries Array of VarInt Numeric ID of the block/item.

Serverbound

Query Block NBT

Used when Shift+F3+I is pressed while looking at a block.

Packet ID State Bound To Field Name Field Type Notes
0x01 Play Server Transaction ID VarInt An incremental ID so that the client can verify that the response matches.
Location Position The location of the block to check.

Tab-Complete (serverbound)

Sent when the client needs to tab-complete a minecraft:ask_server suggestion type.

Packet ID State Bound To Field Name Field Type Notes
0x01 0x05 Play Server Transaction Id VarInt The id received in the tab completion request packet, must match or the client will ignore this packet. Client generates this and increments it each time it sends another tab completion that doesn't get a response.
Text String (32767 32500) All text behind the cursor without the / (e.g. to the left of the cursor in left-to-right languages like English)
Assume Command Boolean If true, the server will parse Text as a command even if it doesn't start with a /. Used in the command block GUI.
Has Position Boolean
Looked At Block Optional Position The position of the block being looked at. Only sent if Has Position is true.

Plugin Message (serverbound)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses a number of plugin channels. These internal channels are prefixed with MC|.

More documentation on this: http://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Note that the length of Data is known only from the packet length, since the packet has no length field of any kind.

Packet ID State Bound To Field Name Field Type Notes
0x0A Play Server Channel String (20) Identifier Name of the plugin channel used to send the data
Data Byte Array Any data, depending on the channel. MC| channels are documented here. The length of this array must be inferred from the packet length.

Edit Book

Packet ID State Bound To Field Name Field Type Notes
0x0B Play Server New book Slot
Is signing Boolean True if the player is signing the book; false if the player is saving a draft.
Hand VarInt enum 0: Main hand, 1: Off hand

When editing a draft, the NBT section of the Slot contains this:

TAG_Compound(''): 1 entry
{
  TAG_List('pages'): 2 entries
  {
    TAG_String(0): 'Something on Page 1'
    TAG_String(1): 'Something on Page 2'
  }
}

When signing the book, it instead looks like this:

TAG_Compound(''): 3 entires
{
  TAG_String('author'): 'Steve'
  TAG_String('title'): 'A Wonderful Book'
  TAG_List('pages'): 2 entries
  {
    TAG_String(0): 'Something on Page 1'
    TAG_String(1): 'Something on Page 2'
  }
}

Query Entity NBT

Used when Shift+F3+I is pressed while looking at an entity.

Packet ID State Bound To Field Name Field Type Notes
0x0C Play Server Transaction ID VarInt An incremental ID so that the client can verify that the response matches.
Entity ID VarInt The ID of the entity to query.

Pick Item

Used to swap out an empty space on the hotbar with the item in the given inventory slot. The Notchain client uses this for pick block functionality (middle click) to retrieve items from the inventory.


Packet ID State Bound To Field Name Field Type Notes
0x15 Play Server Slot to use VarInt See Inventory

The server will first search the player's hotbar for an empty slot, starting from the current slot and looping around to the slot before it. If there are no empty slots, it will start a second search from the current slot and find the first slot that does not contain an enchanted item. If there still are no slots that meet that criteria, then the server will use the currently selected slot.

After finding the appropriate slot, the server swaps the items and then send 3 packets:

  • Set Slot, with window ID set to -2 and slot set to the newly chosen slot and the item set to the item that is now in that slot (which was previously at the slot the client requested)
  • Set Slot, with window ID set to -2 and slot set to the slot the player requested, with the item that is now in that slot and was previously on the hotbar slot
  • Held Item Change, with the slot set to the newly chosen slot.


Craft Recipe Request

A replacement for Prepare Crafting Grid. It appears to behave more or less the same, but the client does not specify where to move the items.

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
0x12 0x16 Play Server Window ID Byte
Recipe VarInt Identifier A recipe ID
Make all Boolean Affects the amount of items processed; true if shift is down when clicked

Recipe Book Data

(previously known as Crafting Book Data)

Packet ID State Bound To Field Name Field Type Notes
0x17 0x1B Play Server Type VarInt Determines the format of the rest of the packet
Type Field Name
0: Displayed Recipe Recipe ID Int Identifer A recipe ID
1: Recipe Book States Crafting Recipe Book Open Boolean Whether the player has the crafting recipe book currently opened/active.
Crafting Recipe Filter Active Boolean Whether the player has the crafting recipe book filter option currently active.
Smelting Recipe Book Open Boolean Whether the player has the smelting recipe book currently opened/active.
Smelting Recipe Filter Active Boolean Whether the player has the smelting recipe book filter option currently active.

The Recipe Book Status type is sent when one of the states changes.


Name Item

Sent as a player is renaming an item in an anvil (each keypress in the anvil UI sends a new MC|ItemName Name Item packet). If the new name is empty, then the item loses its custom name (this is different from setting the custom name to the normal name of the item). The item name may be no longer than 35 characters long, and if it is longer than that, then the rename is silently ignored.

Packet ID State Bound To Field Name Field Type Notes
0x1C Play Server Item name String (32767) The new name of the item

Select Trade

When a player selects a specific trade offered by a villager NPC.

Packet ID State Bound To Field Name Field Type Notes
0x1E Play Server Selected slot Integer VarInt The selected slot int the players current (trading) inventory. (Was a full Integer for the plugin message)

Set Beacon Effect

Changes the effect of the current beacon.

Packet ID State Bound To Field Name Field Type Notes
0x20 Play Server Primary Effect Integer VarInt A Potion ID. (Was a full Integer for the plugin message)
Secondary Effect Integer VarInt A Potion ID. (Was a full Integer for the plugin message)

Update Command Block

Packet ID State Bound To Field Name Field Type Notes
0x22 Play Server
X Int
Y Int
Z Int
Location Position
Command String (32767)
Track output Boolean If false, the output of the previous command will not be stored within the command block.
Mode String VarInt enum One of "SEQUENCE" (0), "AUTO" (1), and "REDSTONE" (2)
Is conditional Boolean
Automatic Boolean
Flags Byte 0x01: Track Output (if false, the output of the previous command will not be stored within the command block); 0x02: Is conditional; 0x04: Automatic

Update Command Block Minecart

Packet ID State Bound To Field Name Field Type Notes
0x23 Play Server Entity ID Int VarInt
Command String
Track Output Boolean If false, the output of the previous command will not be stored within the command block.

Update Structure Block

Packet ID State Bound To Field Name Field Type Notes
0x25 Play Server X Int Tile entity location
Y Int Tile entity location
Z Int Tile entity location
Location Position Block entity location
Action Byte VarInt enum An additional action to perform beyond simply saving the given data; see below
Mode String VarInt enum One of "SAVE" (0), "LOAD" (1), "CORNER" (2), "DATA" (3).
Name String
Offset X Int Byte Between -32 and 32
Offset Y Int Byte Between -32 and 32
Offset Z Int Byte Between -32 and 32
Size X Int Byte Between 0 and 32
Size Y Int Byte Between 0 and 32
Size Z Int Byte Between 0 and 32
Mirror String VarInt enum One of "NONE" (0), "LEFT_RIGHT" (1), "FRONT_BACK" (2).
Rotation String VarInt enum One of "NONE" (0), "CLOCKWISE_90" (1), "CLOCKWISE_180" (2), "COUNTERCLOCKWISE_90" (3).
Metadata String
Ignore entities Boolean
Show air Boolean
Show bounding box Boolean
Integrity Float Between 0 and 1
Seed VarLong
Flags Byte 0x01: Ignore entities; 0x02: Show air; 0x04: Show bounding box

Possible actions:

  • 1 0 - Update data
  • 2 1 - Save the structure
  • 3 2 - Load the structure
  • 4 3 - Detect size

All other values are ignored. The Notchian client uses 1 update data to indicate no special action should be taken (i.e. the done button).

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 340 398)
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.
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 Plugin Request

Used to implement a custom handshaking flow together with Login Plugin Response.

Unlike plugin messages in "play" mode, these messages follow a lock-step request/response scheme, where the client is expected to respond to a request indicating whether it understood. The vanilla client always responds that it hasn't understood, and sends an empty payload.

Packet ID State Bound To Field Name Field Type Notes
0x04 Play Client Message ID VarInt Generated by the server - should be unique to the connection.
Channel Identifier Name of the plugin channel used to send the data
Data Byte Array Any data, depending on the channel. MC| channels are documented here. The length of this array must be inferred from the packet length.

Serverbound

Login Plugin Response

Packet ID State Bound To Field Name Field Type Notes
0x02 Play Client Message ID VarInt Should match ID from server.
Successful Boolean true if the client understands the request, false otherwise. When false, no payload follows.
Data Optional Byte Array Any data, depending on the channel. MC| channels are documented here. The length of this array must be inferred from the packet length.