I will look into that. That may be my fault as I manually migrated ISPConfig installation from one server to another. This required a lot of manual labour including editing of /etc/passwd and other related files, manually copying the /home/admispcong and /root/ispconfig and dumping, editing (for new IPs) and restoring the ispconfig database.
Currently, this "installation" is at 2.2.21.
I will return to this problem on friday.