SDK reference

The Godot GDScript SDK (MultiplayerService autoload), v0.3.0.

Installation & configuration

Copy addons/multiplayer_service into your project and enable the plugin.
configure(public_key) then connect_to_server(url), or connect_using_config() to use the editor-saved credentials.
Guest auth is automatic; player_id is stable across reconnects.

Key methods

Area	Methods
Connection	`configure`, `connect_to_server`, `connect_using_config`, `disconnect_from_server`
Rooms	`create_room`, `join_room`, `leave_room`, `list_players`
Lobbies	`create_lobby`, `list_lobbies`, `join_lobby`, `join_lobby_by_id`
Matchmaking	`join_matchmaking`, `leave_matchmaking`
Events	`send_event`
State sync	`patch_room_state`, `set_entity_state`, `patch_entity_state`, `delete_entity_state`
Debug	`set_debug_enabled`, `get_ping_ms`, `create_debug_report`, `create_debug_report_string`

Signals

Connect to signals for every important event:

Connection — connected, disconnected, welcomed, authenticated, reconnecting, reconnected, reconnect_failed, connection_error.
Rooms — room_created, room_joined, player_joined, player_left, room_players, room_expired.
Lobbies — lobby_created, lobby_list, lobby_joined, lobby_closed.
Matchmaking — matchmaking_queued, match_found, matchmaking_left, matchmaking_timeout.
Events — event_received.
State sync — state_snapshot_received, room_state_changed, entity_state_changed, entity_state_deleted, state_update_rejected.
Errors — sdk_error (structured), error_received.

Error codes

Code	Retryable	Meaning
`malformed_message`	no	The message wasn't a valid envelope.
`unknown_message_type`	no	Unrecognized message type.
`invalid_payload`	no	A required field is missing/invalid.
`room_not_found`	no	No such room/lobby, or it expired.
`room_full`	no	The room/lobby hit its max players.
`payload_too_large`	no	Message over the 16 KB limit.
`rate_limited`	yes	Sending too fast; back off.
`state_forbidden`	no	Not the entity owner / not the room host.
`entity_not_found`	no	Patch/delete on a missing entity.
`state_limit_exceeded`	no	Room hit its entity cap.
`state_too_large`	no	State over the size cap.

Reconnection

After an unexpected drop the SDK reconnects automatically with backoff, reusing the token to resume the same player_id. A heartbeat timeout (default 45s) recovers half-open links. Set rejoin_last_room_on_reconnect = true to re-join the last room by code. disconnect_from_server() is treated as intentional and does not reconnect.

Debug reports

create_debug_report() returns a snapshot (SDK + Godot versions, connection/player state, last errors, last 50 messages, ping). create_debug_report_string() gives copyable JSON for the dashboard's debug bundle viewer.

← Debugging Limits →