Problem:
New created users can´t login to nextcloud, but the login to UMC works.
Solution
Source: Get A Quote - Nextcloud
Nextcloud changed the user model for the product:
For very small installations (<500 users) this is 100% free, though without any service or guarantees. For slightly larger installations (>500 users) we offer Nextcloud Enterprise, with support SLA, security information and all benefits that come with our enterprise product.
You can use to check the count, of the nextcloud users in your LDAP
univention-ldapsearch -LLL '(&(nextcloudEnabled=1)(uid=*))' | grep dn: | wc -l
and via nextcloud
univention-app shell nextcloud sudo -u www-data /var/www/html/occ user:report
If you decide to disable some users for nextloud, and the limit is not longer reached, but enabled users can still not login, you can try to adjust the limit to 600 and restart the docker container. After that the limit is 500 again, but the user can login again.
There might be an issue that, even a lower usercount still triggers the limit.
Than you should make sure you have installed the nextcloud subscription Key.
Check /var/lib/univention-appcenter/apps/nextcloud/data/nextcloud-data/nextcloud.log for messages like that:
message":“Could not create unique name for uid=chr.schein,cn=schueler,cn=users,ou=sun,dc=schein,dc=me.”,“userAgent”:"–",“version”:“25.0.13.2”,“data”:{“app”:“user_ldap”}}
This message could be a hint to that.