You're missing /opt/plesk/php/8.1/etc/php-fpm.d/forum.doitauto.de.conf file. I would copy a known good conf file to that location and see if it helps.
This article might also help you out:
Otherwise, log into your plesk instance to get your license and open a ticket with support.
This article might also help you out:
Otherwise, log into your plesk instance to get your license and open a ticket with support.