Protocol changelog

StartGamePacket

• Clients will now disconnect from servers that do not send a valid JigsawStructureDataPacket before StartGamePacket

PlayerAuthInputPacket

• Optimized Input Data serialization by binding its enum set directly instead of converting through an intermediate list.
• Removed redundant Cereal accessor-presence markers from Input Data, Item Use Transaction, Item Stack Request, Player Block Actions, Vehicle Rotation, and Client Predicted Vehicle. The binary wire format has changed.

MoveActorDeltaPacket

MoveActorDeltaData

• Added mTicks field containing the expected number of ticks before the next movement update is sent to this player, used for client-side interpolation duration

PrimitiveShapesPacket

• Added mLineHeightOverride field to the TextDataPayload for the mExtraDataPayload.

CameraPresetsPacket

• Added Apply Inherited Starting Rotation and Starting Rotation fields to sync the version-gated camera preset starting rotation (MCM-1838)

ServerBoundDiagnosticsPacket

• Modified ServerBoundDiagnosticsPacket to send Entity Position and Dimension information for display in the Minecraft Debugger

RecordStartedPacket

• Added RecordStartedPacket, a server to client packet carrying a BlockPos and a ServerSoundHandle to notify the client that a record started playing at a block position.

Block state serialization

• Vanilla fence blocks now serialize four additional connection block states (minecraft:connection_north, minecraft:connection_east, minecraft:connection_south, minecraft:connection_west), adding new fence permutations to the network block palette

DimensionDataPacket

• Added a required Default Biome string field to each dimension definition in DimensionDataPacket, carrying the identifier of the biome a custom dimension generates with

PlaySoundPacket

• Added a Bypass Listener Range Check boolean field to PlaySoundPacketPayload indicating the receiving client should bypass its volume-based listener range check.

PlaySoundPacket

• Added optional property mPlaybackPositionSeconds to PlaySoundPacket

ContainerType enum

• Added DATA_DRIVEN_CONTAINER for containers backed by the minecraft:container block component

BlockDefinition network payload

• Added the minecraft:container block component so clients can predict interactions with custom container blocks

BossEventPacket

• Removed the redundant Player ID field; servers now identify the player from the packet sender connection

StartGamePacket

• Updated GatheringsConfigurationJoinInfo to use its packet schema, making packet fields optional

ClientboundTextureShiftPacket

• Start actions now use the Enabled field to control whether texture shifts begin enabled; ClientboundTextureShiftPacket remains unused

ClientboundAttributeLayerSyncPacket

• Updated ClientboundAttributeLayerSyncPacket. Added a NoiseAlignment option to EnvironmentAttributeData types.

SetScorePacket

• Changed RemoveScore::Objective Name from being a double optional back a single optional value like it was before

StartGamePacket

• Fixed an issue where LevelSetting's areEducationFeaturesEnabled value was not being serialized using the old serialization system.

ClientboundUpdateSoundDataPacket

• Fixed the event payload binding. The sound event variant was bound once per alternative, which wrote the whole variant seven times per packet and produced eight top-level fields in the docs. It is now a single tagged variant field Event, discriminated by a new SoundDataEventType (uint8) Type tag, matching the pattern used by other variant packets.

API

Changed display data of MessageBox.