Thanks for your support 
@xefil I used the Backup and Restore Script from OH2 described here to backup and restore my config. I have to take a look in that generated zip first.
@Johan_F Sorry, but I don’t understand what you have changed about that mentioned file :-/. Do you mean setting the permissions to that file like e.g.
sudo chmod 666 /usr/lib/systemd/system/openhab2.service
Regards,
Thomas