This page documents the changes from the last stable Minecraft release (currently 1.20.4, protocol 765) to the current pre-release (currently 24w03a, protocol Snapshot 171). Note that this page contains bleeding-edge information that may not be completely or correctly documented.
One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.
Contents
Data types
No changes so far.
Packets
| ID
|
Packet name
|
Documentation
|
| Handshake serverbound
|
| 0x00 |
Handshake |
Current |
Pre
|
| Login clientbound
|
| 0x05 |
Cookie Request (Login) |
|
Pre
|
| Login serverbound
|
| 0x04 |
Cookie Response (Login) |
|
Pre
|
| Configuration clientbound
|
| 0x00 |
Cookie Request (Configuration) |
|
Pre
|
| Configuration serverbound
|
| 0x01 |
Cookie Response (Configuration) |
|
Pre
|
| Play clientbound
|
| 0x16 |
Cookie Request (Play) |
|
Pre
|
| 0x6A |
Store Cookie |
|
Pre
|
| 0x72 |
Transfer |
|
Pre
|
| 0x74 |
Update Attributes |
Current |
Pre
|
| 0x75 |
Entity Effect |
Current |
Pre
|
| Play serverbound
|
| 0x10 |
Cookie Response (Play) |
|
Pre
|
New/modified data types
No changes so far.
Entity Metadata
| Type (VarInt Enum)
|
Value (Varies)
|
Notes
|
| 0
|
Byte
|
|
| 1
|
VarInt
|
|
| 2
|
VarLong
|
|
| 3
|
Float
|
|
| 4
|
String
|
|
| 5
|
Chat
|
|
| 6
|
OptChat (Boolean + Chat)
|
Chat is present if the Boolean is set to true
|
| 7
|
Slot
|
|
| 8
|
Boolean
|
|
| 9
|
Rotation
|
3 Floats: rotation on x, rotation on y, rotation on z
|
| 10
|
Position
|
|
| 11
|
OptPosition (Boolean + Position)
|
Position is present if the Boolean is set to true
|
| 12
|
Direction (VarInt)
|
(Down = 0, Up = 1, North = 2, South = 3, West = 4, East = 5)
|
| 13
|
OptUUID (Boolean + UUID)
|
UUID is present if the Boolean is set to true
|
| 14
|
BlockID (VarInt)
|
| 15
|
OptBlockID (VarInt)
|
0 for absent (implies air); otherwise, a block state ID as per the block state registry
|
| 16
|
NBT
|
|
| 17
|
Particle
|
|
| 18
|
Villager Data
|
3 VarInts: villager type, villager profession, level
|
| 19
|
OptVarInt
|
0 for absent; 1 + actual value otherwise. Used for entity IDs.
|
| 20
|
Pose
|
A VarInt enum: 0: STANDING, 1: FALL_FLYING, 2: SLEEPING, 3: SWIMMING, 4: SPIN_ATTACK, 5: SNEAKING, 6: LONG_JUMPING, 7: DYING, 8: CROAKING, 9: USING_TONGUE, 10: SITTING, 11: ROARING, 12: SNIFFING, 13: EMERGING, 14: DIGGING
|
| 21
|
Cat Variant
|
A VarInt that points towards the CAT_VARIANT registry.
|
| 22
|
Frog Variant
|
A VarInt that points towards the FROG_VARIANT registry.
|
| 23
|
OptGlobalPos (Boolean + GlobalPos)
|
GlobalPos consists of a dimension identifier and Position.
|
| 24
|
Painting Variant
|
A VarInt that points towards the PAINTING_VARIANT registry.
|
| 25
|
Sniffer State
|
A VarInt enum: IDLING = 0, FEELING_HAPPY = 1, SCENTING = 2, SNIFFING = 3, SEARCHING = 4, DIGGING = 5, RISING = 6
|
| 26
|
Armadillo State
|
A VarInt enum: IDLE = 0, ROLLING = 1, SCARED = 2
|
26 27
|
Vector3
|
3 Floats: x, y, z
|
27 28
|
Quaternion
|
4 Floats: x, y, z, w
|
Armadillo
Extends Animal.
| Index
|
Type
|
Meaning
|
Default
|
| 17
|
Armadillo State
|
Armadillo State
|
IDLE
|
Block Actions
No changes so far.
Inventories
No changes so far.
Plugin Channels
No changes so far.
Handshake
Serverbound
Handshake
This causes the server to switch into the target state.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x00
|
Handshaking
|
Server
|
Protocol Version
|
VarInt
|
See protocol version numbers (currently 765 in Minecraft 1.20.4).
|
| Server Address
|
String (255)
|
Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information. Note that SRV records are a simple redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide example.org as server address in addition to connecting to it.
|
| Server Port
|
Unsigned Short
|
Default is 25565. The Notchian server does not use this information.
|
| Next State
|
VarInt Enum
|
1 for Status, 2 for Login, 3 for Transfer.
|
Status
Clientbound
No changes so far.
Serverbound
No changes so far.
Login
Clientbound
Cookie Request (Login)
Requests a cookie that was previously stored.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x05
|
Login
|
Client
|
Key
|
Identifier
|
The identifier of the cookie.
|
Serverbound
Cookie Response (Login)
Response to a Cookie Request (Login) from the server. The Notchian server only accepts responses of up to 5 kiB in size.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x04
|
Login
|
Server
|
Key
|
Identifier
|
The identifier of the cookie.
|
| Has Payload
|
Boolean
|
The payload is only present if the cookie exists on the client.
|
| Payload
|
Optional ByteArray(5120)
|
The data of the cookie, if any.
|
Configuration
Clientbound
Cookie Request (Configuration)
Requests a cookie that was previously stored.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x00
|
Configuration
|
Client
|
Key
|
Identifier
|
The identifier of the cookie.
|
Serverbound
Cookie Response (Configuration)
Response to a Cookie Request (Configuration) from the server. The Notchian server only accepts responses of up to 5 kiB in size.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x01
|
Configuration
|
Server
|
Key
|
Identifier
|
The identifier of the cookie.
|
| Has Payload
|
Boolean
|
The payload is only present if the cookie exists on the client.
|
| Payload
|
Optional ByteArray(5120)
|
The data of the cookie, if any.
|
Play
Clientbound
Cookie Request (Play)
Requests a cookie that was previously stored.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x16
|
Play
|
Client
|
Key
|
Identifier
|
The identifier of the cookie.
|
Store Cookie
Stores some arbitrary data on the client, which persists between server transfers. The Notchian client only accepts cookies of up to 5 kiB in size.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x6A
|
Play
|
Client
|
Key
|
Identifier
|
The identifier of the cookie.
|
| Payload
|
ByteArray(5120)
|
The data of the cookie.
|
Transfer
Notifies the client that it should transfer to the given server. Cookies previously stored are preserved between server transfers.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x72
|
Play
|
Client
|
Host
|
String
|
The hostname of IP of the server.
|
| Port
|
VarInt
|
The port of the server.
|
Update Attributes
Sets attributes on the given entity.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x71
|
Play
|
Client
|
Entity ID
|
VarInt
|
|
| Number Of Properties
|
VarInt
|
Number of elements in the following array.
|
| Property
|
Key Id
|
Array
|
Identifier VarInt Enum
|
See below.
|
| Value
|
Double
|
See below.
|
| Number Of Modifiers
|
VarInt
|
Number of elements in the following array.
|
| Modifiers
|
Array of Modifier Data
|
See Attribute#Modifiers. Modifier Data defined below.
|
Known Key values (see also Attribute#Modifiers):
| Id
|
Key
|
Default
|
Min
|
Max
|
Label
|
| 0
|
generic.armor
|
0.0
|
0.0
|
30.0
|
Armor.
|
| 1
|
generic.armor_toughness
|
0.0
|
0.0
|
20.0
|
Armor Toughness.
|
| 2
|
generic.attack_damage
|
2.0
|
0.0
|
2048.0
|
Attack Damage.
|
| 3
|
generic.attack_knockback
|
0.0
|
0.0
|
5.0
|
Attack Knockback.
|
| 4
|
generic.attack_speed
|
4.0
|
0.0
|
1024.0
|
Attack Speed.
|
| 5
|
generic.block_interaction_range
|
4.5
|
0.0
|
64.0
|
Block Interaction Range.
|
| 6
|
generic.entity_interaction_range
|
3.0
|
0.0
|
64.0
|
Entity Interaction Range.
|
| 7
|
generic.flying_speed
|
0.4
|
0.0
|
1024.0
|
Flying Speed.
|
| 8
|
generic.follow_range
|
32.0
|
0.0
|
2048.0
|
Follow Range.
|
| 9
|
horse.jump_strength
|
0.7
|
0.0
|
2.0
|
Jump Strength.
|
| 10
|
generic.knockback_resistance
|
0.0
|
0.0
|
1.0
|
Knockback Resistance.
|
| 11
|
generic.luck
|
0.0
|
-1024.0
|
1024.0
|
Luck.
|
| 12
|
generic.max_absorption
|
0.0
|
0.0
|
2048.0
|
Max Absorption.
|
| 13
|
generic.max_health
|
20.0
|
1.0
|
1024.0
|
Max Health.
|
| 14
|
generic.movement_speed
|
0.7
|
0.0
|
1024.0
|
Movement Speed.
|
| 15
|
generic.scale
|
1.0
|
0.0625
|
16.0
|
Scale.
|
| 16
|
zombie.spawn_reinforcements
|
0.0
|
0.0
|
1.0
|
Spawn Reinforcements Chance.
|
| 17
|
generic.step_height
|
0.6
|
0.0
|
10.0
|
Step Height.
|
Modifier Data structure:
| Field Name
|
Field Type
|
Notes
|
| UUID
|
UUID
|
|
| Amount
|
Double
|
May be positive or negative.
|
| Operation
|
Byte
|
See below.
|
The operation controls how the base value of the modifier is changed.
- 0: Add/subtract amount
- 1: Add/subtract amount percent of the current value
- 2: Multiply by amount percent
All of the 0's are applied first, and then the 1's, and then the 2's.
Entity Effect
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x72
|
Play
|
Client
|
Entity ID
|
VarInt
|
|
| Effect ID
|
VarInt
|
See this table.
|
| Amplifier
|
Byte
|
Notchian client displays effect level as Amplifier + 1.
|
| Duration
|
VarInt
|
Duration in ticks. (-1 for infinite)
|
| Flags
|
Byte
|
Bit field, see below.
|
| Has Factor Data
|
Boolean
|
Used in DARKNESS effect
|
| Factor Codec
|
NBT Tag
|
See below
|
 |
The following information needs to be added to this page:
|
| What exact effect does the blend bit flag have on the client? What happens if it is used on effects besides DARKNESS?
|
Within flags:
- 0x01: Is ambient - was the effect spawned from a beacon? All beacon-generated effects are ambient. Ambient effects use a different icon in the HUD (blue border rather than gray). If all effects on an entity are ambient, the "Is potion effect ambient" living metadata field should be set to true. Usually should not be enabled.
- 0x02: Show particles - should all particles from this effect be hidden? Effects with particles hidden are not included in the calculation of the effect color, and are not rendered on the HUD (but are still rendered within the inventory). Usually should be enabled.
- 0x04: Show icon - should the icon be displayed on the client? Usually should be enabled.
- 0x08: Blend - should the effect's hard-coded blending be applied? Currently only used in the DARKNESS effect to apply extra void fog and adjust the gamma value for lighting.
Factor Data
| Name
|
Type
|
Notes
|
| padding_duration
|
TAG_INT
|
|
| factor_start
|
TAG_FLOAT
|
|
| factor_target
|
TAG_FLOAT
|
|
| factor_current
|
TAG_FLOAT
|
|
| effect_changed_timestamp
|
TAG_INT
|
| factor_previous_frame
|
TAG_FLOAT
|
| had_effect_last_tick
|
TAG_BOOLEAN
|
Serverbound
Cookie Response (Play)
Response to a Cookie Request (Play) from the server. The Notchian server only accepts responses of up to 5 kiB in size.
| Packet ID
|
State
|
Bound To
|
Field Name
|
Field Type
|
Notes
|
| 0x6A
|
Play
|
Server
|
Key
|
Identifier
|
The identifier of the cookie.
|
| Has Payload
|
Boolean
|
The payload is only present if the cookie exists on the client.
|
| Payload
|
Optional ByteArray(5120)
|
The data of the cookie, if any.
|
