Cannot open IP Address Banning (Fail2Ban) in Plesk panel: No section

Symptoms

When going to Tools & Setting > IP Address Banning (Fail2Ban) the following error messages are displayed:

ERROR No section: 'Definition'

f2bmng failed: ERROR:__main__:No section: 'plesk-one-week-ban'

Cause

Corrupted Fail2Ban installation

Resolution

1. Connect to the server via SSH

2. Remove the fail2ban-related packages (example below is for Ubuntu/Debian):

   # dpkg -P --force-depends fail2ban

   # dpkg -P --force-depends plesk-fail2ban-configurator

3. Rename/back up leftover directories /etc/fail2ban and /var/lib/fail2ban:

   # mv /etc/fail2ban /etc/fail2ban.back

   # mv /var/lib/fail2ban /var/lib/fail2ban.back

4. Reinstall Fail2Ban via Plesk Installer