Spontaneously rejoined to a room which I left, and now can't interact with

[richvdh]

We have seen a number of reports of the following:

• user leaves a room
• at some point later, their client starts showing it again
• Attempts to leave get "Not a known room" or "Room does not exist"
• Attempts to send a message get User @foo:bar not in room !baz:bleh

[richvdh]

I think the cause of this is the state resets caused by #1935. Possibly, another HS ends up with its state wound back to a point at which you were a member of the room, and starts sending events with prev_events which predate your departure. Your own HS then gets confused and starts telling clients that you are in the room (when you really aren't).

[seanenck]

Just for an additional data point:

• I've definitely been hit by Got into a room I didn't join #1629 at least 2 or 3 times over the weekend
• and this issue itself (rejoined to Matrix-HQ oddly enough)

[richvdh]

I've definitely been hit by #1629 at least 2 or 3 times over the weekend
and this issue itself (rejoined to Matrix-HQ oddly enough)

This and #1629 are the same thing as far as I'm concerned, so this doesn't make much sense. Please could you make yourself known on Matrix and explain what you're seeing?

[seanenck]

I can make myself known but I am/was agreeing with you (sorry if that wasn't clear before).

[richvdh]

It appears that @enckse saw two things:

• spontaneously being rejoined to matrix-hq, but in a way that he was able to leave the room again. Raised as Spontaneous leaving/rejoining rooms ["state resets"] #1953.
• Only seeing half the member list, making it appear that he was joined to a room that he had never joined, which is almost certainly an artifact of Rejected events reset the room state #1935.

[richvdh]

this was fixed for @boli:boli.rocks by re-inviting him, after which he was able to reject the invite and resume normal service.

[rubo77]

My synapse thought, I was in #matrix-dev, although I wasn't there. My database had this entry:

select * FROM current_state_events WHERE room_id like '%XqBunHwQIXUiqCaoxq:matrix.org
' and state_key = '@rubo77:mydomain';                      
               event_id                |            room_id             |     type      |        state_key
---------------------------------------+--------------------------------+---------------+--------------------------
 $14713765517956PLlfc:mydomain | !XqBunHwQIXUiqCaoxq:matrix.org | m.room.member | @rubo77:mydomain    

I could fix it by deleting the current state with:

delete FROM current_state_events WHERE room_id = '!id:matrix.org' and state_key = '@rubo77:mydomain';

Then I could rejoin the room and everything is back to normal

[ChazyTheBest]

I got a similar situation:

• Create a new room
• Leave
• Try to join again
• Internal server error (M_UNKNOWN)

With both the web client and riot.im. But the room still exists, and I can see the history (only using riot.im, the synapse web client redirects to home).

[richvdh]

@ChazyTheBest @rubo77 they sound like different issues. Please open new issues.

[richvdh]

Given that #1935 has been fixed, I'm going to close this. #1953 remains as an open issue. If people continue to find themselves spuriously rejoined to rooms, please open new issues - it's easier to close as duplicates than it is to unpick reports of several problems on the same issue.