Symptoms

Activating fail2ban generates errors in Plesk:
ERROR NOK: ('database disk image is malformed',)
ERROR NOK: ('columns jail, path, firstlinemd5 are not unique',)
ERROR NOK: ('database or disk is full',)
ERROR:f2bmng:Command '['/usr/bin/fail2ban-client', 'reload', 'plesk-wordpress']' returned non-zero exit status 255
ERROR:f2bmng:Failed to reload following jails due to errors in configuration: plesk-wordpress

Plesk panel.log

You get the following error message:
fail2ban.transmitter [2431]: WARNING Command ['set', 'plesk-wordpress', 'addlogpath', '/var/www/vhosts/system/elisalf.com/logs/access_log', 'head'] has failed. Received DatabaseError('database disk image is malformed',)

Cause

fail2ban Database errors

Solution

  1. Removefail2ban package withplesk installer utility.
  2. Remove
    fail2ban Database
    # mv /var/lib/fail2ban/fail2ban.sqlite3 /var/lib/fail2ban/fail2ban.sqlite3.bak
  3. Installfail2ban package plesk installer utility.