Ambiguous message: "You attempted to join using a room ID without providing a list of servers to join through."

[rltas]

Steps to reproduce

1. Create a room.
2. Leave the room.
3. Try to "Join the discussion" again from "Historical".

Outcome

What did you expect?

A message telling me that the room doesn't exist / can't be found on the server.

What happened instead?

A message telling me something that confuses me:

Failed to join
You attempted to join using a room ID without providing a list of servers to join through. Room IDs are internal identifiers and cannot be used to join a room without additional information.
If you know a room address, try joining through that instead.

Additional information

In the browser console I see

POST https://matrix-client.matrix.org/_matrix/client/r0/join/!NVfMslxkPhhjsSXnGH%3Amatrix.org 404

Not sure if it's always been like that or only recently because maybe forget_rooms_on_leave has been enabled for matrix.org?

Operating system

No response

Browser information

No response

URL for webapp

app.element.io

Application version

No response

Homeserver

matrix.org

Will you send logs?

No

[JeanPaulLucien]

Was you alone in room?
If all left a room, nobody can join.

[rltas]

Yes. One of our users stumbled upon this and I reproduced it. The problem isn't that the room can't be joined again, but that the message is ambiguous.

I just found element-hq/element-meta#419 and matrix-org/matrix-react-sdk#6048, but that was about permalinks from what I see. The message shouldn't appear in the situation described above imo.

[weeman1337]

Can reproduce as well.