Corrupted login page after auto-update of server on RPi

Nextcloud version (eg, 20.0.5): was 25.0.3.2 before auto-update
Operating system and version (eg, Ubuntu 20.04): nextcloudpi v1.53.0
Apache or nginx version (eg, Apache 2.4.25): ???
PHP version (eg, 7.4): ???

The issue you are facing:

HISTORY

Yesterday, my local NextCloud Clients (Windows, Android, …) showed that my NextCloud service was in “Maintenance Mode”. This is sometimes the case, as I keep “auto update” active in my configuration. When nothing changed for some hours, I decided to have a look on the server via SSH. There I saw the welcome message which encouraged me to update my NCP installation from 1.52.? to v1.53.0 . Which I did in hope to as well get rid of the “maintenance mode”.

PROBLEM

After some minutes following the NCP update, the clients started synchronization again, and I thought, everything was fine again. But this was not the case. Now, although the “proper” NextCloud clients seem to work fine, I can not log into the NectCloud server via web access. When issuing the appropriate address within the address line of my browser, it shows the following content:

So, I can not see any admin status info or do any management.

I guess, this problem is very specific to my system. So, there might be little chance to get rid of the login problem without re-installation of the whole thing. Would like to keep my files (on an external SSD) and my user access configurations…

Any Ideas?

Is this the first time you’ve seen this error?

YES

Steps to replicate it:

always present

The output of your Nextcloud log in Admin > Logging:

[ no access ]

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

[ in a hurry. will get it later ]

The output of your Apache/nginx/system log in /var/log/____:

[ in a hurry. will get it later ]

Output errors in nextcloud.log in /var/www/ or as admin user in top right menu, filtering for errors. Use a pastebin service if necessary.

[ in a hurry. will get it later ]