UCS upgrade to 5.0.0 not authorized issue

Hi there!

I’ve upgraded my Active Directory joined UCS server to version 5.0-0 errata44. I could not login with username “administrator” after the upgrade process (not authorized), so I forced a machine password change and rejoined the USC to Active Directory. So far so good. I’m now able to login with the (domain) administrator BUT no matter where I click on the univention management console I get

Your session has expired, please login again.
Not authorized

SSH login with administrator is also not possible.

Your account has expired; please contact your system administrator

I cannot seccessfully execute the domain join scripts.

Not all installed components have been registered. Please visit the “Domain join” module to register the remaining components.

univention-check-join-status
Warning: 'univention-appcenter' is not configured.
Warning: 'univention-portal' is not configured.
Warning: 'univention-server-overview' is not configured.
Error: Not all install files configured: 3 missing

The administrator can’t login to NextCloud but to Rocket.Chat. Both are AD connected.

All other AD users can log in successfully into the installed apps.

Any thoughts would be much appreciated!

Best regards