Apache2 does not start

Initial situation

The following error message appears in the syslog:

May 23 19:58:27 hostname systemd[1]: apache2.service: cgroup is empty We found out that some configurations have not been deleted by Plesk generating the issue described.

The following error message appears during the Apache2 configuration test:

AH00112: Warning: DocumentRoot [/var/www/vhosts/web127.sr45.firestorm.ch/httpdocs/test] does not exist
AH00543: apache2: bad user name web127
Action 'configtest' failed.

Solution:

1. Make a server backup including all configuration files
2. cd /etc/apache2/plesk.conf.d
3. apache2ctl configtest
4. Notice the user which is displayed in the error message: “apache2: bad user name web127“.
5. grep web127 -R
6. Delete all files output by the ‘grep’ command.
7. You can now rebuild all configuration files during the night as follows:
   # plesk repair web