Pre-release protocol
This page documents the changes from the last stable Minecraft release (currently 1.20.2, protocol 764) to the current pre-release (currently 23w41a, protocol Snapshot 156). 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
NBT
The NBT specification was changed so that the root tag is no longer required to be a Compound Tag when sent over the network.
Presently in the pre-release, only Compound Tag and String Tag types are used as root, but the Notchian server/client implementation is able to handle NBT Tags of any type.
Chat
The Chat type is now serialized as a NBT Tag instead of a JSON String.
| Name | Size (bytes) | Encodes | Notes |
|---|---|---|---|
| Chat | ≥ 1 ≤ (262144×4) + 3 |
See Chat | Encoded as a String with max length of 262144. |
| Chat | Varies | See Chat | Encoded as a NBT Tag, with the type of tag used depending on the case:
|
This affects all packets and data types containing Chat fields:
- Disconnect (login)
- Disconnect (configuration)
- Resource Pack (configuration)
- Boss Bar
- Command Suggestions Response
- Disconnect (play)
- Disguised Chat Message
- Map Data
- Open Screen
- Player Chat Message
- Combat Death
- Player Info Update
- Resource Pack (play)
- Server Data
- Set Action Bar Text
- Update Objectives
- Update Teams
- Set Subtitle Text
- Set Title Text
- System Chat Message
- Set Tab List Header And Footer
- Update Advancements
- Slot data type (values in the item NBT field)
- Chat entity metadata type
- OptChat entity metadata type
Packets
| ID | Packet name | Documentation | |
|---|---|---|---|
| Play clientbound | |||
| 0x20 | Game Event | Current | Pre |
New/modified data types
No changes so far.
Entity Metadata
Abstract Vehicle
Extends Entity.
| Index | Type | Meaning | Default | |
|---|---|---|---|---|
| 8 | VarInt | Shaking power | 0 | |
| 9 | VarInt | Shaking direction | 1 | |
| 10 | Float | Shaking multiplier | 0.0 | |
Abstract Minecart
Extends Abstract Vehicle.
| Index | Type | Meaning | Default | |
|---|---|---|---|---|
| 8 | VarInt | Shaking power | 0 | |
| 9 | VarInt | Shaking direction | 1 | |
| 10 | Float | Shaking multiplier | 0.0 | |
| 11 | VarInt | Custom block ID and damage | 0 | |
| 12 | VarInt | Custom block Y position (in 16ths of a block) | 6 | |
| 13 | Boolean | Show custom block | false | |
Boat
Extends Abstract Vehicle.
| Index | Type | Meaning | Default | |
|---|---|---|---|---|
| 8 | VarInt | Time since last hit | 0 | |
| 9 | VarInt | Forward direction | 1 | |
| 10 | Float | Damage taken | 0.0 | |
| 11 | VarInt | Type (0=oak, 1=spruce, 2=birch, 3=jungle, 4=acacia, 5=dark oak) | 0 | |
| 12 | Boolean | Is left paddle turning | false | |
| 13 | Boolean | Is right paddle turning | false | |
| 14 | VarInt | Splash timer | 0 | |
Block Actions
No changes so far.
Inventories
No changes so far.
Plugin Channels
No changes so far.
Status
Clientbound
No changes so far.
Serverbound
No changes so far.
Login
Clientbound
No changes so far.
Serverbound
No changes so far.
Configuration
Clientbound
No changes so far.
Serverbound
No changes so far.
Play
Clientbound
Game Event
Used for a wide variety of game events, from weather to bed use to game mode to demo messages.
| Packet ID | State | Bound To | Field Name | Field Type | Notes |
|---|---|---|---|---|---|
| 0x20 | Play | Client | Event | Unsigned Byte | See below. |
| Value | Float | Depends on Event. |
Events:
| Event | Effect | Value |
|---|---|---|
| 0 | No respawn block available | Note: Displays message 'block.minecraft.spawn.not_valid' (You have no home bed or charged respawn anchor, or it was obstructed) to the player. |
| 1 | Begin raining | |
| 2 | End raining | |
| 3 | Change game mode | 0: Survival, 1: Creative, 2: Adventure, 3: Spectator. |
| 4 | Win game | 0: Just respawn player. 1: Roll the credits and respawn player. Note that 1 is only sent by notchian server when player has not yet achieved advancement "The end?", else 0 is sent. |
| 5 | Demo event | 0: Show welcome to demo screen. 101: Tell movement controls. 102: Tell jump control. 103: Tell inventory control. 104: Tell that the demo is over and print a message about how to take a screenshot. |
| 6 | Arrow hit player | Note: Sent when any player is struck by an arrow. |
| 7 | Rain level change | Note: Seems to change both sky color and lighting. Rain level ranging from 0 to 1. |
| 8 | Thunder level change | Note: Seems to change both sky color and lighting (same as Rain level change, but doesn't start rain). It also requires rain to render by notchian client. Thunder level ranging from 0 to 1. |
| 9 | Play pufferfish sting sound | |
| 10 | Play elder guardian mob appearance (effect and sound) | |
| 11 | Enable respawn screen | 0: Enable respawn screen. 1: Immediately respawn (sent when the doImmediateRespawn gamerule changes).
|
| 12 | Limited crafting | 0: Disable limited crafting. 1: Enable limited crafting (sent when the doLimitedCrafting gamerule changes).
|
| 13 | Start waiting for level chunks | Instructs the client to begin the waiting process for the level chunks. Sent by the server after the level is cleared on the client and is being re-sent (either during the first, or subsequent reconfigurations). |
Serverbound
No changes so far.
