minecraft_protocol/packets/catalog-control-states.md

Packet Catalog — Control States

Complete packet tables for the small, fully-enumerable states: Handshaking, Status, Login, Configuration.

Baseline: 1.21.1 (protocol 773). Version deltas noted inline. Sources:

• minecraft-data/data/pc/1.21.1/protocol.json — IDs and field types (machine-readable ground truth)
• ViaVersion ClientboundLoginPackets.java, ServerboundLoginPackets.java — enum ordinal cross-check
• ViaVersion ClientboundConfigurationPackets1_20_2.java, 1_20_5.java, ServerboundConfigurationPackets1_20_2.java, 1_20_5.java — version delta cross-check
• minecraft.wiki/w/Java_Edition_protocol/Packets — field names and semantic descriptions

See also: ../03-handshake.md · ../04-status-ping.md · ../05-login-encryption.md · ../06-configuration.md

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Handshaking State

The handshaking state has no clientbound packets. There is exactly one modern serverbound packet; the legacy ping byte is a legacy artifact that predates the formal state machine.

Serverbound

ID	Name	Direction	Field summary
0x00	Handshake	C→S	protocolVersion (VarInt), serverHost (String ≤255), serverPort (u16), nextState (VarInt: 1=Status, 2=Login, 3=Transfer¹)
0xFE	Legacy Server List Ping	C→S	payload (u8, always 0x01); pre-1.7 clients only — modern servers recognize and respond with legacy format²

¹ nextState=3 (Transfer) added in 1.20.5 (protocol 766). ² 0xFE is outside the normal VarInt packet-ID space; servers detect it by the raw byte value.

Source: minecraft-data/data/pc/1.21.1/protocol.json → handshaking.toServer.types mappings {"0x00": "set_protocol", "0xfe": "legacy_server_list_ping"}.

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Status State

Two packets in each direction. IDs are stable since 1.7.

Serverbound

ID	Name	Direction	Field summary
0x00	Status Request	C→S	No fields; triggers Status Response
0x01	Ping Request	C→S	time (i64, ms timestamp)

Clientbound

ID	Name	Direction	Field summary
0x00	Status Response	S→C	response (String; JSON with version, players, description, favicon)
0x01	Pong Response	S→C	time (i64; echo of Ping Request's timestamp)

Source: minecraft-data/data/pc/1.21.1/protocol.json → status.toServer / status.toClient mappings.

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Login State

Login was extended in 1.20.2 (Login Acknowledged) and 1.20.5 (Cookie Request/Response).

Serverbound

ID	Name	Direction	Since	Field summary
0x00	Login Start	C→S	1.7	username (String ≤16), playerUUID (UUID)
0x01	Encryption Response	C→S	1.7	sharedSecret (ByteArray, VarInt-length-prefixed; RSA-encrypted), verifyToken (ByteArray, VarInt-length-prefixed; RSA-encrypted)
0x02	Login Plugin Response	C→S	1.13	messageId (VarInt; echoes request), data (optional restBuffer; absent if unhandled)
0x03	Login Acknowledged	C→S	1.20.2	No fields; transitions server to Configuration state
0x04	Cookie Response	C→S	1.20.5	key (String; resource location), value (optional ByteArray ≤5120 bytes)

Clientbound

ID	Name	Direction	Since	Field summary
0x00	Disconnect (Login)	S→C	1.7	reason (String; JSON text component)
0x01	Encryption Request	S→C	1.7	serverId (String, always "" in modern protocol¹), publicKey (ByteArray; DER-encoded RSA), verifyToken (ByteArray; random nonce), shouldAuthenticate (bool; false = offline-mode)
0x02	Login Success	S→C	1.7	uuid (UUID), username (String ≤16), properties (Array of {name:String, value:String, signature:Optional<String>}), strictErrorHandling (bool; added 1.20.5²)
0x03	Set Compression	S→C	1.8	threshold (VarInt; packets ≥ this size get compressed; −1 = disable)
0x04	Login Plugin Request	S→C	1.13	messageId (VarInt; unique per request), channel (String; resource location), data (restBuffer; plugin-defined payload)
0x05	Cookie Request (Login)	S→C	1.20.5	cookie (String; resource location key)

¹ Server ID was used for session-server auth in very old versions; now always empty string. ² strictErrorHandling field added in 1.20.5 — older clients receive a shorter Login Success.

Source: minecraft-data/data/pc/1.21.1/protocol.json → login.toServer / login.toClient mappings. ViaVersion cross-check: ClientboundLoginPackets.java ordinals 0–5 match; ServerboundLoginPackets.java ordinals 0–4 match.

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Configuration State

Added in 1.20.2 (protocol 764). Not present in 1.20 or earlier.

The Configuration state runs between Login Acknowledged and Finish Configuration. Its purpose: push registry data, feature flags, resource packs, and tags before the client enters Play. The state can be re-entered from Play (server sends Start Configuration).

The packet set expanded again in 1.20.5 (protocol 766): Cookie, Transfer, Store Cookie, resource-pack split (push/pop vs. unified), and Select Known Packs were added, shifting most IDs. 1.21 added Custom Report Details and Server Links (CB 0x0F/0x10, SB 0x08/0x09).

Serverbound

ID	Name	Direction	Since	Field summary
0x00	Client Information	C→S	1.20.2	locale (String ≤16), viewDistance (i8), chatFlags (VarInt), chatColors (bool), skinParts (u8 bitmask), mainHand (VarInt: 0=left,1=right), enableTextFiltering (bool), allowServerListings (bool)
0x01	Cookie Response	C→S	1.20.5	key (String; resource location), value (optional ByteArray ≤5120 bytes)
0x02	Plugin Message	C→S	1.20.2	channel (String; resource location), data (restBuffer; minecraft:brand → UTF-8 VarInt-prefixed client brand string)
0x03	Acknowledge Finish Configuration	C→S	1.20.2	No fields; transitions to Play state
0x04	Keep Alive	C→S	1.20.2	keepAliveId (i64; echoes server's value)
0x05	Pong	C→S	1.20.2	id (i32; echoes server's Ping id)
0x06	Resource Pack Response	C→S	1.20.2	uuid (UUID; 1.20.5+¹), result (VarInt: 0=Success,1=Declined,2=Failed,3=Accepted,4=Downloaded,5=InvalidUrl,6=FailedReload,7=Discarded)
0x07	Select Known Packs	C→S	1.20.5	packs (Array of {namespace:String, id:String, version:String})
0x08	Custom Report Details	C→S	1.21	details (Array of {key:String, value:String}; debug crash info)²
0x09	Server Links Response	C→S	1.21	links (Array; echoes known-type or custom-text link list)²

¹ In 1.20.2–1.20.4 the resource pack response had no UUID field; UUID was added when resource-pack-push/pop split was introduced in 1.20.5. ² IDs 0x08 and 0x09 confirmed added in 1.21: absent from ServerboundConfigurationPackets1_20_5 (ends at 0x07) and present in 1.21.1 protocol.json. ViaVersion passes them through in the SB direction without a new enum file — ServerboundConfigurationPackets1_20_5 covers 1.20.5 through 1.21.x (no SB enum file in v1_20_5to1_21 package). Source: ViaVersion/.../protocols/v1_20_5to1_21/packet/ClientboundConfigurationPackets1_21.java (CB side confirmed) + minecraft-data/data/pc/1.21.1/protocol.json configuration.toServer.

ID shift note (1.20.2 → 1.20.5 serverbound):

ID (1.20.2)	Name	ID (1.20.5+)
0x00	Client Information	0x00 (no change)
0x01	Plugin Message	0x02 (+1)
0x02	Finish Configuration	0x03 (+1)
0x03	Keep Alive	0x04 (+1)
0x04	Pong	0x05 (+1)
0x05	Resource Pack	0x06 (+1)
—	Cookie Response	0x01 (new)
—	Select Known Packs	0x07 (new)

Source: minecraft-data/data/pc/1.21.1/protocol.json → configuration.toServer; ViaVersion/.../ServerboundConfigurationPackets1_20_2.java vs ServerboundConfigurationPackets1_20_5.java.

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Clientbound

ID	Name	Direction	Since	Field summary
0x00	Cookie Request	S→C	1.20.5	cookie (String; resource location key to retrieve)
0x01	Plugin Message	S→C	1.20.2	channel (String), data (restBuffer; minecraft:brand sends server brand)
0x02	Disconnect	S→C	1.20.2	reason (anonymousNbt; text component as NBT, not JSON string)
0x03	Finish Configuration	S→C	1.20.2	No fields; server signals config complete, waits for SB Acknowledge
0x04	Keep Alive	S→C	1.20.2	keepAliveId (i64; client must echo within ~30s or be kicked)
0x05	Ping	S→C	1.20.2	id (i32; client echoes in Pong)
0x06	Reset Chat	S→C	1.20.2	No fields; clears client chat session state
0x07	Registry Data	S→C	1.20.2	id (String; registry resource location), entries (Array of {key:String, value:Optional<anonymousNbt>}); one packet per registry
0x08	Remove Resource Pack	S→C	1.20.5	uuid (optional UUID; absent = remove all)
0x09	Add Resource Pack	S→C	1.20.5	uuid (UUID), url (String), hash (String, SHA-1 hex), forced (bool), promptMessage (Optional<anonymousNbt> text component)
0x0A	Store Cookie	S→C	1.20.5	key (String; resource location), value (ByteArray ≤5120 bytes)
0x0B	Transfer	S→C	1.20.5	host (String), port (VarInt); redirects client to another server
0x0C	Feature Flags	S→C	1.20.2	features (Array<String>; resource location list of active experimental features)
0x0D	Update Tags	S→C	1.20.2	tags (Array of {tagType:String, tags:Array of {tagName:String, entries:Array<VarInt>}})
0x0E	Select Known Packs	S→C	1.20.5	packs (Array of {namespace:String, id:String, version:String}); client replies SB Select Known Packs
0x0F	Custom Report Details	S→C	1.21	details (Array of {key:String, value:String}); appears in crash reports¹
0x10	Server Links	S→C	1.21	links (Array of {hasKnownType:bool, knownType:ServerLinkType (if known), unknownType:NbtComponent (if custom), url:String})¹

¹ 0x0F and 0x10 confirmed added in 1.21: ClientboundConfigurationPackets1_20_5 ends at SELECT_KNOWN_PACKS (0x0E); ClientboundConfigurationPackets1_21 (in v1_20_5to1_21 package) adds CUSTOM_REPORT_DETAILS (0x0F) and SERVER_LINKS (0x10). Source: ViaVersion/.../protocols/v1_20_5to1_21/packet/ClientboundConfigurationPackets1_21.java.

ID shift note (1.20.2 → 1.20.5 clientbound):

ID (1.20.2)	Name	ID (1.20.5+)
0x00	Plugin Message	0x01 (+1)
0x01	Disconnect	0x02 (+1)
0x02	Finish Configuration	0x03 (+1)
0x03	Keep Alive	0x04 (+1)
0x04	Ping	0x05 (+1)
0x05	Registry Data	0x07 (+2)
0x06	Resource Pack	split: 0x08/0x09
0x07	Feature Flags	0x0C (+5)
0x08	Update Tags	0x0D (+5)
—	Cookie Request	0x00 (new)
—	Reset Chat	0x06 (new)
—	Store Cookie	0x0A (new)
—	Transfer	0x0B (new)
—	Select Known Packs	0x0E (new)

Source: minecraft-data/data/pc/1.21.1/protocol.json → configuration.toClient; ViaVersion/.../ClientboundConfigurationPackets1_20_2.java vs ClientboundConfigurationPackets1_20_5.java.