I recently realized, that AppArmor always fails on startup, and this is what
service status returns. I don't quite get this and don't really know how to go about this. This might just as well be in the Newbies section, but I thought it might be more appropriate here.

● apparmor.service - LSB: AppArmor initialization
Loaded: loaded (/etc/init.d/apparmor; bad; vendor preset: enabled)
Active: failed (Result: exit-code) since Do 2018-05-31 22:15:59 CEST; 39min ago
Docs: man:systemd-sysv-generator(8)
Process: 392 ExecStart=/etc/init.d/apparmor start (code=exited, status=123)

Mai 31 22:15:56 user apparmor[392]: Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd
Mai 31 22:15:56 user apparmor[392]: AppArmor parser error for /etc/apparmor.d/usr.sbin.mysqld in /etc/apparmor.d/usr.sbin.mysqld at line 9: Could not open 'abstractions/mysql'
Mai 31 22:15:56 user apparmor[392]: Skipping profile in /etc/apparmor.d/disable: usr.bin.firefox
Mai 31 22:15:56 user apparmor[392]: Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd
Mai 31 22:15:56 user apparmor[392]: AppArmor parser error for /etc/apparmor.d/usr.sbin.mysqld in /etc/apparmor.d/usr.sbin.mysqld at line 9: Could not open 'abstractions/mysql'
Mai 31 22:15:59 user apparmor[392]: ...fail!
Mai 31 22:15:59 user systemd[1]: apparmor.service: Control process exited, code=exited status=123
Mai 31 22:15:59 user systemd[1]: Failed to start LSB: AppArmor initialization.
Mai 31 22:15:59 user systemd[1]: apparmor.service: Unit entered failed state.
Mai 31 22:15:59 user systemd[1]: apparmor.service: Failed with result 'exit-code'.

Try this: https://askubuntu.com/questions/7672...-exit-code-123