Apache2 and nextcloud not starting

I have a NextCloudPi running on a QNAP NAS.
The NextCloudPi image was pulled in April 2020, so it will be v1.20.1. I regulary updated the NCP within the container.

After updating the firmware version of my QNAP NAS the nextcloud is inaccessible.
The container starts with multiple error messages, first was
tail: cannot open '/data/ncdata/data/nextcloud.log' for reading: No such file or directory
The directory /data/ncdata did not exist (it was /data/nextcloud), so I solved this creating a softlink /data/ncdata targeting /data/nextcloud.

Now I am stuck on the error that apache2 does not start.

Error messages are:

Stopping apache
apache2: Syntax error on line 225 of /etc/apache2/apache2.conf: Could not open config directory /etc/apache2/sites-enabled: Too many levels of symbolic links
Action 'graceful-stop' failed.
The Apache error log may have more information.
Making /etc/apache2/sites-available persistent ...
mv: failed to access '/data/etc/apache2/sites-available': Too many levels of symbolic links

I am grateful for any suggestions.