Hi all

I managed to get my Nextcloud 28 connected to OpenProject successfully, and all was working like a charm! That was yesterday. I remember during my tests that at some point I had to log into Nextcloud and 'grant access' to OP. This tells me there is some cookie that was set. So yesterday everything worked excellently. However, I came back today, wanted to check out a few more things, and I ran into this error:

{
 "headers": {
   "normalizedNames": {},
   "lazyUpdate": null
 },
 "status": 500,
 "statusText": "Internal Server Error",
 "url": "https://projects.example.com/api/v3/work_packages/235/file_links?filters=[{%22storage%22:{%22operator%22:%22=%22,%22values%22:[%222%22]}}]",
 "ok": false,
 "name": "HttpErrorResponse",
 "message": "Http failure response for https://projects.example.com/api/v3/work_packages/235/file_links?filters=[{%22storage%22:{%22operator%22:%22=%22,%22values%22:[%222%22]}}]: 500 Internal Server Error",
 "error": {
   "_type": "Error",
   "errorIdentifier": "urn:openproject-org:api:v3:errors:InternalServerError",
   "message": "An internal error has occurred. unexpected token at '<?xml version=\"1.0\"?>\n<ocs>\n <meta>\n  <status>failure</status>\n  <statuscode>996</statuscode>\n  <message>Internal Server Error\n</message>\n </meta>\n <data/>\n</ocs>\n'"
 }
}

As you can clearly see, I have no access to my Nextcloud Storages. Checking from the admin pages, the integration shows all green.

All of my services run behind an HAProxy loadbalancer with SSL termination. So Nextcloud reaches OpenProject on HTTPS, but via the load balancer, and vice versa. I don't know if I need to set something special here? I also have both services connected via LDAP. So the same user is logged into both OP and NC via LDAP.

This baffles me as this was fully functional and might I say, working really nicely yesterday. But this session expiration thing is a kind of a deal-breaker, seeing as you cannot get to your work done 'yesterday'.

Any way I can fix this? TIA for any help.