Cannot load Community Rooms if leaving room added

[KazamaSion]

Description

If I create a room with no local address, add the room to the community, then leave the room, the community cannot load the room list anymore.
It's not a network issue. A newly created community with no operations can see the room list (even with no rooms, it at least can load).
The only way to solve is to destroy and rebuild the community.

Temporary example of the bugged community: +ftqu8z5yo:matrix.org

Steps to reproduce

• Create a room with no local address
• Add the room to the community
• Leave the room

Logs being sent: yes

Bugged community:

Normal Community:

Version information

• Platform: web and desktop

For the web app:

• Browser: Chrome 80
• OS: Windows 10
• URL: riot.im/app

For the desktop app:

• OS: Windows
• Version: 1.5.15

[prasket]

I are also seeing this same behavior in one of the communities on a homeserver I help host. Taking this info I am going to dig into the database to see if there is a way to remove bad room from there to resolve. I will update with info I find.

[prasket]

OK I can confirm that if you remove the rooms from the group_rooms table in postrgres the rooms will go back to showing again.

[hlesueur]

Hello, I'm having the same issue, but my community (epb) is on matrix.org, so I have no access to the db
Anyone maintining the database would be able to help me removing this broken room from the database?
Thanks!

[KazamaSion]

Since there's no dev replying to this issue, I think this is no the right place to feedback (maybe?)
So here is the question: where to submit this issue?

[hlesueur]

I also put it in #riot-web:matrix.org, but no answer until now

I may have a suggestion on how to fix this, but that's nothing I can add on my own.
option 1:
upon quitting a room, make a simple test whether the room gets empty when the last user quits it , then if yes remove the room from the community it's attached to
(although I don't know how simple it is to test if it's in a community, unless the flair-badge is automatically set in the room settings when the room is added to the community ... anyways, I never got the meaning/purpose of the flair except for the esthetic of messages)

option2:
test the community in the database regularly for empty rooms , and remove them from the community and/or throw a message to the admin of the community with a link to the room.

[Twi1ightSparkle]

https://newvector.zammad.com/#ticket/zoom/3139

[hlesueur]

Hello @Twi1ightSparkle, thanks for the ticket. I've been watching zammad, but it's quite an empty room.
Is anyone looking at this? Should I do something?
thank you

[turt2live]

Apologies for the delayed response here - we don't reply to every issue, nor do we spend a lot of time looking at issues related to the communities feature these days. The whole feature is slated for rewrite at the moment, which is why we're not spending much time triaging these things.

From a high-level glance it looks like this is probably a Synapse issue, and potentially a recentish regression. Considering their implementation has received just as much attention as ours (ie: very little), I am not all that surprised it has regressed, unfortunately.

Best advice I can give is to be careful about the rooms which get included in a community :(

[Twi1ightSparkle]

@hlesueur
We only use Zammad internally, which is why you don't see anything. I will check if we think doing the database fix suggested above is safe, and if yes I will do that for you.

[hlesueur]

Thanks for both your answers.
I understand you may have some load here! thanks for the work by the way.

@Twi1ightSparkle are you suggesting doing for me the fix (eg software fix), or doing the manual removal of empty room just for my broken db?
in any case, thanks

[Twi1ightSparkle]

Synapse issue matrix-org/synapse#4891

[hlesueur]

Thank you so much @Twi1ightSparkle it's repaired... !

[t3chguy]

This is fixed by Spaces landing in Beta in next Release