Error 503 Service temporarily down - Greenbone OS

When starting a task we get this error:
Status code: 503
Status message: Service temporarily down

I have already tried to restart the server with no luck.

We do not have root account permission to login via SSH. Login currently only possible with “admin”. We cannot use “systemctl”.
And I also do not see any file called “openvassd.log”.

GSM Type: CE
GOS Version: 4.2.10

Thank you and best regards,

This is a EOL version of the CE based on a EOL version of GOS. Please setup a fresh version of the most recent GCE 6.0.3.