Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.13.1, protocol 401) to the current pre-release (currently 1.13.2-pre2, protocol 403). 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.

Slot

Name	Type	Meaning
Present	Boolean	True if the item is present; false if it is empty.
Item ID	Short Optional VarInt	The item ID. A value of -1 signifies that the slot is empty, and no further data follows. Not present if present is false. Item IDs are distinct from block IDs; see Data Generators for more information
Item Count	Optional Byte	Not present if Item ID is -1 present is false.
NBT	Optional NBT	Not present if Item ID is -1 present is false. If 0, there is no NBT data, and no further data follows. Otherwise the byte is the start of an NBT blob as shown below:

  COMPOUND ''
    LIST 'StoredEnchantments'
      COMPOUND
        SHORT 'id'
        SHORT 'lvl'
      END
      COMPOUND
        ...
      END
      ...
    END
    INT 'Unbreakable'
    ...
  END

See NBT for more information about the NBT format, and here for the contained information and its format. Note that tool durability is included in NBT, among other things.

Packets

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre

New/modified data types

No changes so far.

Entity Metadata

No changes so far.

Block Actions

No changes so far.

Play

Clientbound

No changes so far.

Serverbound

No changes so far.

Handshaking

Clientbound

There are no clientbound packets in the Handshaking state, since the protocol immediately switches to a different state after the client sends the first packet.

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 401 403)
			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

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.