Setting up fail2ban (0.9.6-2) ...
Created symlink /etc/systemd/system/multi-user.target.wants/fail2ban.service → /lib/systemd/system/fail2ban.service.
Job for fail2ban.service failed because the control process exited with error code.
See "systemctl status fail2ban.service" and "journalctl -xe" for details.
invoke-rc.d: initscript fail2ban, action "start" failed.
● fail2ban.service - Fail2Ban Service
  Loaded: loaded (/lib/systemd/system/fail2ban.service; enabled; vendor preset: enabled)
  Active: activating (auto-restart) (Result: exit-code) since Wed 2019-09-11 09:26:04 CEST; 3ms ago
    Docs: man:fail2ban(1)
  Process: 1301 ExecStart=/usr/bin/fail2ban-client -x start (code=exited, status=255)

Sep 11 09:26:04 Web-GS-Froxlor systemd[1]: fail2ban.service: Unit entered failed state.
Sep 11 09:26:04 Web-GS-Froxlor systemd[1]: fail2ban.service: Failed with result 'exit-code'.
dpkg: error processing package fail2ban (--configure):
subprocess installed post-installation script returned error exit status 1
Processing triggers for libc-bin (2.24-11+deb9u4) ...
Processing triggers for systemd (232-25+deb9u12) ...
Errors were encountered while processing:
fail2ban
E: Sub-process /usr/bin/dpkg returned an error code (1)