Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.10.2, protocol 210) to the current pre-release (currently 16w42a, protocol 312). 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

No changes so far.

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre
Play clientbound
0x03	Spawn Mob	Current	Pre
0x09	Update Block Entity	Current	Pre
0x0E	Tab-Complete (clientbound)	Current	Pre
0x1B	Entity Status	Current	Pre
0x24	Map	Current	Pre
0x45	Title	Current	Pre
0x48	Collect Item	Current	Pre
Play serverbound
0x02	Chat Message (serverbound)	Current	Pre
0x1C	Player Block Placement	Current	Pre

New/modified data types

Objects

Objects are spawned via Spawn Object. See Object Data for more details.

ID	Name	x, z	y
1	Boat	1.5	0.6
2	Item Stack (Slot)	0.25	0.25
3	Area Effect Cloud	?	?
10	Minecart	0.98	0.7
50	Activated TNT	0.98	0.98
51	EnderCrystal	2.0	2.0
60	Tipped arrow (projectile; also used for regular arrows)	0.5	0.5
61	Snowball (projectile)	0.25	0.25
62	Egg (projectile)	0.25	0.25
63	FireBall (ghast projectile)	1.0	1.0
64	FireCharge (blaze projectile)	0.3125	0.3125
65	Thrown Enderpearl	0.25	0.25
66	Wither Skull (projectile)	0.3125	0.3125
67	Shulker Bullet	0.3125	0.3125
68	Llama spit	0.25	0.25
70	Falling Objects	0.98	0.98
71	Item frames	varies	varies
72	Eye of Ender	0.25	0.25
73	Thrown Potion	0.25	0.25
75	Thrown Exp Bottle	0.25	0.25
76	Firework Rocket	0.25	0.25
77	Leash Knot	0.5	0.5
78	ArmorStand	0.5	2.0
79	Evocation Fangs	0.8	0.5
90	Fishing Float	0.25	0.25
91	Spectral Arrow	0.5	0.5
93	Dragon Fireball	0.3125	0.3125

Since release 1.6, all minecarts are spawned with object type 10 and their functionality is then specified in the Data field within the packet. Also, their visual appearance may be sent via the Entity Metadata packet.

Mobs

Mobs are spawned via Spawn Mob. There are two extra mob types in the code that refer to mobs classes that can never spawn: Mob and Monster (they are always subclasses, aka another more specific type).

Type	Name	x, z	y	ID
4	ElderGuardian	0.85	0.85	minecraft:elder_guardian
5	WitherSkeleton	0.7	2.4	minecraft:wither_skeleton
6	Stray	0.6	1.99	minecraft:stray
23	Husk	0.6	1.95	minecraft:husk
27	ZombieVillager	0.6	1.95	minecraft:zombie_villager
28	SkeletonHorse	1.396484	1.6	minecraft:skeleton_horse
29	ZombieHorse	1.396484	1.6	minecraft:zombie_horse
31	Donkey	1.396484	1.6	minecraft:donkey
32	Mule	1.396484	1.6	minecraft:mule
33	EvocationFangs	0.5	0.8	minecraft:evocation_fangs
34	EvocationIllager	0.6	1.95	minecraft:evocation_illager
35	Vex	0.4	0.8	minecraft:vex
36	VindicationIllager	0.6	1.95	minecraft:vindication_illager
48	Mob	N/A	N/A	N/A
49	Monster	N/A	N/A	N/A
50	Creeper	0.6	1.7	minecraft:creeper
51	Skeleton	0.6	1.99	minecraft:skeleton
52	Spider	1.4	0.9	minecraft:spider
53	Giant	0.6 * 6	1.8 * 6	minecraft:giant
54	Zombie	0.6	1.8	minecraft:zombie
55	Slime	0.51000005 * size	0.51000005 * size	minecraft:slime
56	Ghast	4	4	minecraft:ghast
57	PigZombie	0.6	1.8	minecraft:zombie_pigman
58	Enderman	0.6	2.9	minecraft:enderman
59	CaveSpider	0.7	0.5	minecraft:cave_spider
60	Silverfish	0.4	0.3	minecraft:silverfish
61	Blaze	0.6	1.8	minecraft:blaze
62	LavaSlime (Magma Cube)	0.51000005 * size	0.51000005 * size	minecraft:magma_cube
63	EnderDragon	16.0	8.0	minecraft:ender_dragon
64	WitherBoss	0.9	3.5	minecraft:wither
65	Bat	0.5	0.9	minecraft:bat
66	Witch	0.6	1.8	minecraft:witch
67	Endermite	0.4	0.3	minecraft:endermite
68	Guardian	0.85	0.85	minecraft:guardian
69	Shulker	1	1	minecraft:shulker
90	Pig	0.9	0.9	minecraft:pig
91	Sheep	0.9	1.3	minecraft:sheep
92	Cow	0.9	1.4	minecraft:cow
93	Chicken	0.4	0.7	minecraft:chicken
94	Squid	0.8	0.8	minecraft:squid
95	Wolf	0.6	0.85	minecraft:wolf
96	MushroomCow (Mooshroom)	0.9	1.3	minecraft:mooshroom
97	SnowMan	0.7	1.9	minecraft:snowman
98	Ozelot (Ocelot)	0.6	0.8	minecraft:ocelot
99	VillagerGolem (Iron Golem)	1.4	2.7	minecraft:villager_golem
100	EntityHorse	1.396484	1.6	minecraft:horse
101	Rabbit	0.4	0.5	minecraft:rabbit
102	PolarBear	1.3	1.4	minecraft:polar_bear
103	Llama	1.3964844	1.87	minecraft:llama
104	LlamaSpit	0.25	0.25	minecraft:llama_spit
120	Villager	0.6	1.95	minecraft:villager

EvocationIllager

Extends Monster.

Index	Type	Meaning
12	Byte	Unknown (Probably hands up animation)

Vex

Extends Monster.

Index	Type	Meaning
12	Byte	Bit mask	Meaning
		0x01	Is in attack mode

VindicationIllager

Extends Monster.

Index	Type	Meaning
12	Byte	Bit mask	Meaning
		0x01	Has target (aggressive state)

EvocationFangs

Extends Entity.

AbstractSkeleton

Extends Monster.

Index	Type	Meaning
12	Boolean	Is swinging arms

Skeleton

Extends AbstractSkeleton.

Index	Type	Meaning
12	VarInt	Type (Normal = 0, Wither = 1, Stray = 2)
13	Boolean	Is swinging arms (Used to animate arms for melee attacks; only used when the skeleton does not have a bow in its hand)

Wither Skeleton

Extends AbstractSkeleton.

Stray

Extends AbstractSkeleton.

Zombie

Extends Monster.

Index	Type	Meaning
12	Boolean	Is baby
13	VarInt	Zombie type (0 for zombie, profession+1 for villagers, 6 for Husk) Unused
14	Boolean	Is converting
15 14	Boolean	Are hands held up

Zombie Villager

Extends Zombie.

Index	Type	Meaning
15	Boolean	Is converting
16	VarInt	Profession

Husk

Extends Zombie.

Guardian

Extends Monster.

Index	Type	Meaning
12	Byte	Bit mask	Meaning
		0x02	is retracting spikes
		0x04	is elderly
12	Boolean	Is retracting spikes
13	VarInt	Target EID

ElderGuardian

Extends Guardian.

AbstractHorse

Extends Animal.

Index	Type	Meaning
13	Byte	Bit mask	Meaning
		0x01	Unused
		0x02	Is Tame
		0x04	Is saddled
		0x08	Has Chest
		0x10	Is Bred (not used on the Notchian server; controlled via the unused Bred NBT flag)
		0x20	Is eating
		0x40	Is rearing (on hind legs)
		0x80	Is mouth open
14	OptUUID	Owner

Horse

Extends AbstractHorse.

Index	Type	Meaning
15	VarInt	Variant (Color & Style)
16	VarInt	Armor

ZombieHorse

Extends AbstractHorse.

SkeletonHorse

Extends AbstractHorse.

ChestedHorse

Extends AbstractHorse.

Index	Type	Meaning
15	Boolean	Has Chest

Donkey

Extends ChestedHorse.

Llama

Extends ChestedHorse.

Index	Type	Meaning
16	Integer	Strength (number of columns of 3 slots in the llama's inventory once a chest is equipped)
17	Integer	Carpet color (a dye color, or -1 if no carpet equipped)
18	Integer	Variant (0: llama_creamy.png, 1: llama_white.png, 2: llama_brown.png, 3: llama_gray.png)

Mule

Extends ChestedHorse.

Villager

Extends Ageable.

Index	Type	Meaning
13	VarInt	Profession (Farmer = 0, Librarian = 1, Priest = 2, Blacksmith = 3, Butcher = 4, Nitwit = 5)

Shulker

Extends Golem.

Index	Type	Meaning
12	Direction	Facing direction
13	OptPosition	Attachment position
14	Byte	Shield height
15	Byte	Color (dye color, default of purple)

LlamaSpit

Extends Entity.

Inventory

Window Type	Description
minecraft:chest	Chest, large chest, or minecart with chest
minecraft:crafting_table	Crafting table
minecraft:furnace	Furnace
minecraft:dispenser	Dispenser
minecraft:enchanting_table	Enchantment table
minecraft:brewing_stand	Brewing stand
minecraft:villager	Villager
minecraft:beacon	Beacon
minecraft:anvil	Anvil
minecraft:hopper	Hopper or minecart with hopper
minecraft:dropper	Dropper
minecraft:shulker_box	Shulker box
EntityHorse	Horse, donkey, or mule, or Llama

Shulker box

Shulker box slots

This is the window that is opened when the player right-clicks on a shulker box chest.

Slot range	Description
0–26	box slots
27–53	main inventory
54–62	hotbar

Llama

Llama slots

The inventory that appears when a tamed llama is right-clicked and has a chest, or when the player's inventory is opened while riding a tamed llama. Depending on the value of the strength field, the number of chest rows may vary (max is 5, so 15 slots).

There still is a saddle slot, even though it cannot be used and is invisible.

Slot positions within the llama inventory vary - slot 2 may be at (1,0) or at (0,1) depending on the number of columns.

Slot range	Description
0	saddle
1	carpet
2-(2+3*Strength)	llama inventory
(2+3*Strength)+1-(2+3*Strength)+27	player inventory
(2+3*Strength)+28-(2+3*Strength)+35	hotbar

• 

  Unchested llama

• 

  Llama with strength 1

• 

  Llama with strength 2

• 

  Llama with strength 3

• 

  Llama with strength 4

• 

  Llama with strength 5

Block Actions

Shulker Box

Animates the shulker box's shell opening.

Action IDs

There is only one action: 1, which updates the number of players who are looking in the shulker box.

Action param

If the action is 1, updates the number of players who have the shulker box open. If 0, the shulker box enters its closing animation; if 1, the shulker box enters its opening animation.

Handshaking

Clientbound

No changes so far.

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 210 312)
			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

Play

Clientbound

Spawn Mob

Sent by the server when a mob entity is spawned.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x03	Play	Client	Entity ID	VarInt
			Entity UUID	UUID
			Type	Unsigned Byte VarInt	The type of mob. See Entities#Mobs
			X	Double
			Y	Double
			Z	Double
			Yaw	Angle
			Pitch	Angle
			Head Pitch	Angle
			Velocity X	Short	Same units as Entity Velocity
			Velocity Y	Short	Same units as Entity Velocity
			Velocity Z	Short	Same units as Entity Velocity
			Metadata	Entity Metadata

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 SpawnPotentials of a mob spawner
• 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
• 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 (unclear if there is any actual data)

Tab-Complete (clientbound)

The server responds with a list of auto-completions of the last word sent to it. In the case of regular chat, this is a player username. Command names and parameters are also supported. The client lists these in the order that they are in the array. The client sorts these alphabetically before listing them.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x0E	Play	Client	Count	VarInt	Number of elements in the following array
			Matches	Array of String	One eligible command, note that each command is sent separately instead of in a single string, hence the need for Count

Entity Status

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1B	Play	Client	Entity ID	Int
			Entity Status	Byte Enum	See below

Entity Status	Meaning
0	Spawn tipped arrow particle effects
1	Reset a mob spawner minecart's timer (unused by the client?)
1	Create rabbit running particles
2	Entity hurt animation
3	Entity died animation
4	Iron Golem throwing up arms
6	Wolf/Ocelot/Horse taming — Spawn “heart” particles
7	Wolf/Ocelot/Horse tamed — Spawn “smoke” particles
8	Wolf shaking water — Trigger the shaking animation
9	Mark item use as finished (ie, eating finished, drinking finished)
10	Sheep eating grass
10	Ignite TNT minecart
11	Iron Golem handing over a rose
12	Villager mating — Spawn “heart” particles
13	Spawn particles indicating that a villager is angry and seeking revenge
14	Spawn happy particles near a villager
15	Witch animation — Spawn “magic” particles
16	Play zombie converting into a villager sound
17	Firework exploding
18	Animal in love (ready to mate) — Spawn “heart” particles
19	Reset squid rotation
20	Spawn explosion particle — works for some living entities
21	Play guardian sound — works for every entity
22	Enables reduced debug for the given player
23	Disables reduced debug for the given player
24–28	Sets the op permission level 0–4 for the connected player
29	Shield block sound
30	Shield break sound
31	For a fishing rod bobber, if the hooked entity is this player, tug that player toward the caster of the rod
32	Armorstand hit sound
33	Entity hurt due to thorns (play thorns sound, perform normal hurt animation)
34	Puts away an iron golem's poppy
35	Plays the Totem of Undying animation

Map

Updates a rectangular area on a map item.

Packet ID	State	Bound To	Field Name		Field Type		Notes
0x24	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	Array	Byte	0xF0 = Direction, 0x0F = Type
				X		Byte
				Z		Byte
			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
10-15	Unused (blue square)

Title

Packet ID	State	Bound To	Field Name		Field Type	Notes
0x45	Play	Client	Action		VarInt Enum
			Action	Field Name
			0: set title	Title Text	Chat
			1: set subtitle	Subtitle Text	Chat
			2: set action bar	Action bar text	Chat	Behaves the same as with position 2 in Chat Message (clientbound)
			2 3: set times and display	Fade In	Int	Ticks to spend fading in
				Stay	Int	Ticks to keep the title displayed
				Fade Out	Int	Ticks to spend out, not when to start fading out
			3 4: hide	no fields	no fields
			4 5: reset	no fields	no fields

“Hide” makes the title disappear, but if you run times again the same title will appear. “Reset” erases the text.

The title is visible on screen for Fade In + Stay + Fade Out ticks.

Collect Item

Sent by the server when someone picks up an item lying on the ground — its sole purpose appears to be the animation of the item flying towards you. It doesn't destroy the entity in the client memory, and it doesn't add it to your inventory. The server only checks for items to be picked up after each Player Position (and Player Position And Look) packet sent by the client.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x48	Play	Client	Collected Entity ID	VarInt
			Collector Entity ID	VarInt
			Pickup Item Count	VarInt	Seems to be 1 for XP orbs, otherwise the number of items in the stack.

Serverbound

Chat Message (serverbound)

Used to send a chat message to the server. The message may not be longer than 100 256 characters or else the server will kick the client.

If the message starts with a /, the server will attempt to interpret it as a command. Otherwise, the server will broadcast the same chat message to all players on the server (including the player that sent the message), prepended with player's name. Specifically, it will respond with a translate chat component, "chat.type.text" with the first parameter set to the display name of the player (including some chat component logic to support clicking the name to send a PM) and the second parameter set to the message.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x02	Play	Server	Message	String	The client sends the raw input, not a Chat component

Player Block Placement

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

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.