Description

A remote user was invited to a portal room created by the mautrix telegram bridge, causing the bridge kicking them out as soon as they tried to join. They now are in a room with unread messages that they can't configure, leave or purge. Not even force_purge helps. It purges forever until the server is restarted.
When a purge is invoked, an error is thrown in the serverlog: sync_partial_state_room-0 - Failed to get state for roomid at <FrozenEventV3 event_id ... We can't get valid state history., giving up!
Receiving room state via the api returns nothing and runs forever as well.

Steps to reproduce

• login with the https://github.com/mautrix/telegram bot
• invite an innocent, not logged into telegram remote matrix user to a matrix mirrored room the bot has created before automatically
• have the user join
• the bot will remove the user throwing This chat does not have a bot relaying messages for unauthenticated users
• the user now won't be able to do anything with the room and has a permanent unread notification

Homeserver

pragma-messenger.ch

Synapse Version

1.76.0

Installation Method

pip (from PyPI)

Database

PostgreSQL

Workers

Multiple workers

Platform

Debian 11, no containers or vms.

Configuration

Presence and Message retention are turned on. The Mjolnir module is installed.

Relevant log output

2023-02-12 09:54:10,821 - synapse.handlers.federation - 1924 - ERROR - sync_partial_state_room-0 - Failed to get state for !BViUDwYyFqaSxzDVuu:tchncs.de at <FrozenEventV3 event_id=$OsWs6l7AXqdA32_PRKAkfX7wk4y-5ojQeY9tfatVzBM, type=m.room.member, state_key=@wuethrich:pragma-messenger.ch, outlier=False> from tchncs.de because ERROR 403: We can't get valid state history., giving up!
2023-02-12 12:22:21,244 - synapse.http.matrixfederationclient - 709 - WARNING - sync_partial_state_room-0-$OsWs6l7AXqdA32_PRKAkfX7wk4y-5ojQeY9tfatVzBM-$npMAIwUs-g4ABVY53p3rK5E8oe8-ptcJ2PzGHjkHprA - {GET-O-1} [tchncs.de] Request failed: GET matrix://tchncs.de/_matrix/federation/v1/state_ids/%21BViUDwYyFqaSxzDVuu%3Atchncs.de?event_id=%24npMAIwUs-g4ABVY53p3rK5E8oe8-ptcJ2PzGHjkHprA: HttpResponseException('403: Forbidden')

Anything else that would be useful to know?

The room was already purged on tchncs.de in an attempt to help the remote server – but with no luck (it's gone on tchncs.de tho). The affected room has room version 6.