Pre-release protocol

Under construction In light of the recent release of Minecraft 1.9, this article still contains some changes between 1.8.9 and 1.9, which are currently being merged into Protocol. If you want to contribute, please coordinate with us in #mcdevs, and ping Fenhl before making any edits.

This page documents the changes from the last stable Minecraft release (currently 1.9, protocol 107) to the current pre-release (currently 1.9, protocol 107). 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
Play clientbound
0x17	Set Cooldown	Current	Pre
0x19	Named Sound Effect	Current	Pre
0x1B	Entity Status	Current	Pre
0x1D	Unload Chunk	Current	Pre
0x20	Chunk Data	Current	Pre
0x24	Map	Current	Pre
0x25	Entity Relative Move	Current	Pre
0x26	Entity Look And Relative Move	Current	Pre
0x29	Vehicle Move	Current	Pre
0x2C	Combat Event	Current	Pre
0x2E	Player Position And Look	Current	Pre
0x2F	Use Bed	Current	Pre
0x3A	Attach Entity	Current	Pre
0x3C	Entity Equipment	Current	Pre
0x40	Set Passengers	Current	Pre
0x41	Teams	Current	Pre
0x47	Sound Effect	Current	Pre
0x4A	Entity Teleport	Current	Pre
0x4B	Entity Properties	Current	Pre
0x4C	Entity Effect	Current	Pre
Play serverbound
0x00	Teleport Confirm		Pre
0x14 0x01	Tab-Complete	Current	Pre
0x01 0x02	Chat Message	Current	(unchanged)
0x16 0x03	Client Status	Current	Pre
0x15 0x04	Client Settings	Current	Pre
0x0F 0x05	Confirm Transaction	Current	(unchanged)
0x11 0x06	Enchant Item	Current	(unchanged)
0x0E 0x07	Click Window	Current	(unchanged)
0x0D 0x08	Close Window	Current	(unchanged)
0x17 0x09	Plugin Message	Current	(unchanged)
0x02 0x0A	Use Entity	Current	Pre
0x00 0x0B	Keep Alive	Current	(unchanged)
0x04 0x0C	Player Position	Current	(unchanged)
0x06 0x0D	Player Position And Look	Current	(unchanged)
0x05 0x0E	Player Look	Current	(unchanged)
0x03 0x0F	Player	Current	(unchanged)
0x10	Vehicle Move (serverbound)		Pre
0x11	Steer Boat		Pre
0x13 0x12	Player Abilities	Current	(unchanged)
0x07 0x13	Player Digging	Current	Pre
0x0B 0x14	Entity Action	Current	Pre
0x0C 0x15	Steer Vehicle	Current	(unchanged)
0x19 0x16	Resource Pack Status	Current	(unchanged)
0x09 0x17	Held Item Change	Current	(unchanged)
0x10 0x18	Creative Inventory Action	Current	(unchanged)
0x12 0x19	Update Sign	Current	Pre
0x0A 0x1A	Animation	Current	Pre
0x18 0x1B	Spectate	Current	(unchanged)
0x08 0x1C	Player Block Placement	Current	Pre
0x1D	Use Item		Pre
Status clientbound
0x00	Response	Current	(unchanged)
0x01	Pong	Current	(unchanged)
Status serverbound
0x00	Request	Current	(unchanged)
0x01	Ping	Current	(unchanged)
Login clientbound
0x00	Disconnect	Current	(unchanged)
0x01	Encryption Request	Current	(unchanged)
0x02	Login Success	Current	(unchanged)
0x03	Set Compression	Current	(unchanged)
Login serverbound
0x00	Login Start	Current	(unchanged)
0x01	Encryption Response	Current	(unchanged)

New/modified data types

None so far.

Handshaking

Clientbound

No changes so far.

Serverbound

No changes so far.

Play

Clientbound

Entity Relative Move

This packet is sent by the server when an entity moves less then 1024 blocks; if an entity moves more than 1024 blocks Entity Teleport should be sent instead.

This packet allows at most 1024 blocks movement in any direction, because short range is from -32768 to -32767.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x15 0x25	Play	Client	Entity ID	VarInt
			Delta X	Byte Short	Change in X position as a Fixed-Point number (currentX * 32 - prevX * 32) * 128
			Delta Y	Byte Short	Change in Y position as a Fixed-Point number (currentY * 32 - prevY * 32) * 128
			Delta Z	Byte Short	Change in Z position as a Fixed-Point number (currentZ * 32 - prevZ * 32) * 128
			On Ground	Boolean

Entity Look And Relative Move

This packet is sent by the server when an entity rotates and moves. Since a short range is limited from -32768 to 32767, and movement is offset of fixed-point numbers, this packet allows at most 1024 blocks movement in any direction. (-32768/32 == -1024)

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x17 0x26	Play	Client	Entity ID	VarInt
			Delta X	Byte Short	Change in X position as a Fixed-Point number (currentX * 32 - prevX * 32) * 128
			Delta Y	Byte Short	Change in Y position as a Fixed-Point number (currentY * 32 - prevY * 32) * 128
			Delta Z	Byte Short	Change in Z position as a Fixed-Point number (currentZ * 32 - prevZ * 32) * 128
			Yaw	Angle	New angle, not a delta
			Pitch	Angle	New angle, not a delta
			On Ground	Boolean

Vehicle Move

Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x29	Play	Client	X	Double	Absolute position (X coordinate)
			Y	Double	Absolute position (Y coordinate)
			Z	Double	Absolute position (Z coordinate)
			Yaw	Float	Absolute rotation on the vertical Axis, in degrees
			Pitch	Float	Absolute rotation on the horizontal Axis, in degrees

Combat Event

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x42 0x2C	Play	Client	Event		VarInt Enum	Determines the layout of the remaining packet
			Event	Field Name
			0: enter combat	no fields	no fields
			1: end combat	Duration	VarInt
				Entity ID	Int
			2: entity dead	Player ID	VarInt
				Entity ID	Int
				Message	String Chat

Player Position And Look

Updates the player's position on the server.

If the distance between the last known position of the player on the server and the new position set by this packet is greater than 100 meters, the client will be kicked for “You moved too quickly :( (Hacking?)”.

Also if the fixed-point number of X or Z is set greater than 3.2E7D the client will be kicked for “Illegal position”.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0, -1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw in degrees of a player standing at point (x0, z0) and looking towards point (x, z) can be calculated with:

l = x-x0
w = z-z0
c = sqrt( l*l + w*w )
alpha1 = -arcsin(l/c)/PI*180
alpha2 =  arccos(w/c)/PI*180
if alpha2 > 90 then
    yaw = 180 - alpha1
else
    yaw = alpha1

You can get a unit vector from a given yaw/pitch via:

x = -cos(pitch) * sin(yaw)
y = -sin(pitch)
z =  cos(pitch) * cos(yaw)

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x08 0x2E	Play	Client	X	Double	Absolute or relative position, depending on Flags
			Y	Double	Absolute or relative position, depending on Flags
			Z	Double	Absolute or relative position, depending on Flags
			Yaw	Float	Absolute or relative rotation on the X Axis, in degrees
			Pitch	Float	Absolute or relative rotation on the Y Axis, in degrees
			Flags	Byte	Bit field, see below
			Teleport ID	VarInt	Client should confirm this packet with Teleport Confirm containing the same Teleport ID

About the Flags field:

<Dinnerbone> It's a bitfield, X/Y/Z/Y_ROT/X_ROT. If X is set, the x value is relative and not absolute.

Field	Bit
X	0x01
Y	0x02
Z	0x04
Y_ROT	0x08
X_ROT	0x10

Attach Entity

This packet is sent when a player has been attached to an entity (e.g. Minecart).

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1B 0x3A	Play	Client	Entity ID	Int	Attached entity's EID
			Vehicle ID	Int	Vechicle's Entity ID. Set to -1 to detach
			Leash	Boolean	If true leashes the entity to the vehicle

Entity Equipment

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x04 0x3C	Play	Client	Entity ID	VarInt	Entity's EID
			Slot	Short VarInt Enum	Equipment slot. 0: main hand, 1: off hand, 1–4 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet)
			Item	Slot

Set Passengers

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x40	Play	Client	Entity ID	VarInt	Vehicle's EID
			Passenger Count	VarInt	Number of passengers in the array.
Passengers	Array of VarInt	EIDs of entity's passengers

Teams

Creates and updates teams.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x3E 0x41	Play	Client	Team Name	String	A unique name for the team. (Shared with scoreboard).
			Mode	Byte Enum	0: create team, 1: remove team, 2: update team info; 3: add players to team; 4: remove players from team
			Team Display Name	Optional String	Only if Mode is 0 or 2.
			Team Prefix	Optional String	Only if Mode is 0 or 2. Displayed before the players' name that are part of this team.
			Team Suffix	Optional String	Only if Mode is 0 or 2. Displayed after the players' name that are part of this team.
			Friendly Fire	Optional Byte	Only if Mode is 0 or 2. 0 for off, 1 for on, 3 for seeing friendly invisibles.
			Name Tag Visibility	Optional String	Only if Mode is 0 or 2. always, hideForOtherTeams, hideForOwnTeam, never.
			Collision Rule	Optional String	Only if Mode is 0 or 2. always, pushOtherTeams, pushOwnTeam, never
			Color	Optional Byte	Only if Mode is 0 or 2. Same as Chat colors.
			Player Count	Optional VarInt	Only if Mode is 0 or 3 or 4. Number of players in the array.
			Players	Optional Array of String	Only if Mode is 0 or 3 or 4. Players to be added/remove from the team. Max 40 characters so may be uuid's later.

Sound Effect

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x47	Play	Client	Sound ID	VarInt	ID of hardcoded sound event (events)
			Sound Category	VarInt Enum	The category that this sound will be played from (current categories)
			Effect Position X	Int	Effect X multiplied by 8
			Effect Position Y	Int	Effect Y multiplied by 8
			Effect Position Z	Int	Effect Z multiplied by 8
			Volume	Float	1.0 is 100%, capped between 0.0 and 1.0 by vanilla client
			Pitch	Unsigned Byte	Float multiplied by 63.5, capped between 0.5 and 2.0 by vanilla client

Entity Teleport

This packet is sent by the server when an entity moves more than 1024 blocks.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x18 0x4A	Play	Client	Entity ID	VarInt
			X	Int Double
			Y	Int Double
			Z	Int Double
			Yaw	Angle	New angle, not a delta
			Pitch	Angle	New angle, not a delta
			On Ground	Boolean

Entity Properties

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x20 0x4B	Play	Client	Entity ID		VarInt
			Number Of Properties		Int		Number of elements in the following array
			Property	Key	Array	String	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	20.0	0.0	Double.MaxValue 1024.0	Max Health
generic.followRange	32.0	0.0	2048.0	Follow Range
generic.knockbackResistance	0.0	0.0	1.0	Knockback Resistance
generic.movementSpeed	0.699999988079071	0.0	Double.MaxValue 1024.0	Movement Speed
generic.attackDamage	2.0	0.0	Double.MaxValue 2048.0	Attack Damage
generic.attackSpeed	4.0	0.0	1024.0	Attack Speed
horse.jumpStrength	0.7	0.0	2.0	Jump Strength
zombie.spawnReinforcements	0.0	0.0	1.0	Spawn Reinforcements Chance

Modifier Data structure:

Field Name	Field Type	Notes
UUID	UUID
Amount	Double
Operation	Byte

Entity Effect

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1D 0x4C	Play	Client	Entity ID	VarInt
			Effect ID	Byte	See this table
			Amplifier	Byte	Notchian client displays effect level as Amplifier + 1
			Duration	VarInt	Seconds
			Hide Particles	Boolean Byte

Map Chunk Bulk

Replaced by multiple Chunk Data packets.

Update Entity NBT

Wasn't used for anything.

Serverbound

Teleport Confirm

Sent by client as confirmation of Player Position And Look packet.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Play	Server	Teleport ID	VarInt

Tab-Complete

Sent when the user presses tab while writing text.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x14 0x01	Play	Server	Text	String	All text behind the cursor (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.

Client Status

Sent when the client is ready to complete login and when the client is ready to respawn after death.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x16 0x03	Play	Server	Action ID	VarInt Enum	See below

Action ID values:

Action ID	Action
0	Perform respawn
1	Request stats
2	Taking Inventory achievement Open Inventory

Client Settings

Sent when the player connects, or when settings are changed.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x15 0x04	Play	Server	Locale	String	e.g. en_GB
			View Distance	Byte	Client-side render distance, in chunks
			Chat Mode	Byte VarInt Enum	0: enabled, 1: commands only, 2: hidden
			Chat Colors	Boolean	“Colors” multiplayer setting
			Displayed Skin Parts	Unsigned Byte	Skin parts, see note below
			Main Hand	VarInt Enum	0: Left, 1: Right

Displayed Skin Parts flags:

• Bit 0 (0x01): Cape enabled
• Bit 1 (0x02): Jacket enabled
• Bit 2 (0x04): Left Sleeve enabled
• Bit 3 (0x08): Right Sleeve enabled
• Bit 4 (0x10): Left Pants Leg enabled
• Bit 5 (0x20): Right Pants Leg enabled
• Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Use 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
0x02 0x0A	Play	Server	Target	VarInt
			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

Vehicle Move (serverbound)

Sent when a player moves in a vehicle. Fields are the same as in Player Position And Look. Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x10	Play	Server	X	Double	Absolute position (X coordinate)
			Y	Double	Absolute position (Y coordinate)
			Z	Double	Absolute position (Z coordinate)
			Yaw	Float	Absolute rotation on the vertical Axis, in degrees
			Pitch	Float	Absolute rotation on the horizontal Axis, in degrees

Steer Boat

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x11	Play	Server	Boolean	Unknown
			Boolean	Unknown 2

Player Digging

Sent when the player mines a block. A Notchian server only accepts digging packets with coordinates within a 6-unit radius of the player's position.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x07 0x13	Play	Server	Status	Byte Enum	The action the player is taking against the block (see below)
			Location	Position	Block position
			Face	Byte Enum	The face being hit (see below)

Status can be one of seven values:

Value	Meaning	Notes
0	Started digging
1	Cancelled digging	Sent when the player lets go of the Mine Block key (default: left click)
2	Finished digging	Sent when the client thinks it is finished
3	Drop item stack	Triggered by using the Drop Item key (default: Q) with the modifier to drop the entire selected stack (default: depends on OS). Location is always set to 0/0/0, Face is always set to -Y.
4	Drop item	Triggered by using the Drop Item key (default: Q). Location is always set to 0/0/0, Face is always set to -Y.
5	Shoot arrow / finish eating	Location is always set to 0/0/0, Face is always set to Special.
6	Swap item in hand	Used to swap or assign an item to the second hand. Location is always set to 0/0/0, Face is always set to -Y.

The Face field can be one of the following values, representing the face being hit (or the Special value used for “shoot arrow / finish eating”):

Value	Offset	Face
0	-Y	Bottom
1	+Y	Top
2	-Z	North
3	+Z	South
4	-X	West
5	+X	East
255	—	Special

Entity Action

Sent at least when crouching, leaving a bed, or sprinting. To send action animation to client use 0x28. The client will send this with Action ID = 3 when “Leave Bed” is clicked.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0B 0x14	Play	Server	Entity ID	VarInt	Player ID
			Action ID	VarInt Enum	The ID of the action, see below
			Jump Boost	VarInt	Horse jump boost. Ranged from 0 to 100.

Action ID can be one of the following values:

ID	Action
0	Crouch
1	Uncrouch
2	Leave bed
3	Start sprinting
4	Stop sprinting
5	Start Jump with horse
6	Stop Jump with horse
7	Open ridden horse inventory
8	Start Elytra Flying

“Open inventory” is now sent via the Client Status packet.

Update Sign

This message is sent from the client to the server when the “Done” button is pushed after placing a sign.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x12 0x19	Play	Server	Location	Position	Block Coordinates
			Line 1	Chat String	First line of text in the sign
			Line 2	Chat String	Second line of text in the sign
			Line 3	Chat String	Third line of text in the sign
			Line 4	Chat String	Fourth line of text in the sign

Animation

Sent when the player's arm swings.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0A 0x1A	Play	Server	Hand	VarInt Enum	Hand used for the animation

Player Block Placement

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x08 0x1C	Play	Server	Location	Position	Block position
			Face	Byte VarInt Enum	The face on which the block is placed (as documented at Player Digging)
			Held Item	Slot
			Hand	VarInt Enum	The hand from which the block is placed; 0: main hand, 1: off hand
			Cursor Position X	Unsigned Byte	The position of the crosshair on the block, from 0 to 15 increasing from west to east
			Cursor Position Y	Unsigned Byte	The position of the crosshair on the block, from 0 to 15 increasing from bottom to top
			Cursor Position Z	Unsigned Byte	The position of the crosshair on the block, from 0 to 15 increasing from north to south

In normal operation (i.e. placing a block), this packet is sent once, with the values set normally.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to one pixel in the default resource pack. For example, let's say a slab is being placed against the south face of a full block. The Cursor Position X will be higher if the player was pointing near the right (east) edge of the face, lower if pointing near the left. The Cursor Position Y will be used to determine whether it will appear as a bottom slab (values 0–7) or as a top slab (values 8–15). The Cursor Position Z should be 15 since the player was looking at the southernmost part of the block.

This packet has a special case where X, Y, Z, and Direction are all -1. (Note that Y is unsigned so set to 255.) This special packet indicates that the currently held item for the player should have its state updated such as eating food, pulling back bows, using buckets, etc.

Special note on using buckets: When using buckets, the Notchian client might send two packets: first a normal and then a special case. The first normal packet is sent when you're looking at a block (e.g. the water you want to scoop up). This normal packet does not appear to do anything with a Notchian server. The second, special case packet appears to perform the action — based on current position/orientation and with a distance check — it appears that buckets can only be used within a radius of 6 units.

Use Item

Sent when pressing the Use Item key (default: right click) with an item in hand.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1D	Play	Server	Hand	VarInt Enum	Hand used for the animation

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.