Cannot read properties of undefined (reading 'id')

[juliushaertl]

Sentry reported a quite frequent console error, that only seems there since "29.0.4 RC1"

https://nextcloud-gmbh.sentry.io/share/issue/0d2e881a7a144773a4460df9cb99acd1/

[max-nextcloud]

This is odd. I have not been able to reproduce it locally nor on the instance in question yet.
I wonder if this is related to our cleanup of the old sessions. But missing sessions should result in a 403 and then the message to the user to please reload the page.

[max-nextcloud]

I tried to reproduce this in various ways:

• Editing with two users in the 29.0.4 version locally.
• On cloud.nextcloud.com trying various things.
• Setting up 29.0.2 locally and migrating to 29.0.4

I still failed to reproduce it. What I did run into was a situation where sessions was empty because during the update Nextcloud responded with a 200 maintenance page on push and sync. Even though this caused exceptions in the same function it does not seem related.

[max-nextcloud]

Looking at the code this is probably caused by the list of sessions not including any with the current id.
In this case sessions.find will return undefined and this.currentSession is set to undefined.

I see two possible causes:

1. The server responds to a sync request with a list of sessions that does not include a session with the same id as the one that was used to authenticate the request.
2. The currentSession id changed in the meantime. Maybe this even is a response to an old request that gets handled after the document changed or so. (Which might point to collectives as there one can change pages fairly quickly).

[juliushaertl]

URLs seem mostly from files, collectives is just a low amount, top most is a read only share (from the app tutorials), but could just be due to the amout of people browsing it.

[juliushaertl]

Interestingly browsers are just chromium based ones

[max-nextcloud]

uuuhhh... we have this routine to clean up old sessions during the request. That happens after auth. So maybe one can still authenticate with a session and then have it cleaned up.

update: but we only do this during create and close. Create does not require any auth anyway - so maybe this happens when automatically reconnecting and the old session is still around somehow. Since the last update we don't clear the sync service anymore if i remember correctly.

[max-nextcloud]

I was able to trigger an inconsistent state by switching the network off and on again. After a while yjs will attempt to reopen the websocket, calling SyncService.open which fails to open a new connection but still continues. Afterwards sync services _receiveSteps fails as this.#connection is undefined.

This happens a few times until the editor shows the reconnect button. I suspect it's basically the polling backend continuing in the backend.

[juliushaertl]

I also couldn't trigger the issue but I noticed when opening a read only link and keeping the browser running for a while we sometimes have additional create requests without a previous close