Logrotate error for fail2ban
Solution 1:
ERROR Unable to contact server. Is it running?
Your fail2ban service isn't running start it!
service fail2ban start
or whatever starts it on your Ubuntu.
Solution 2:
Add "notifempty" to /etc/logrotate.d/fail2ban. If fail2ban is installed but not running the log will be empty and will not be rotated.