16.04 - Job for fail2ban.service failed because the control process exited with error code - Ask Ubuntu

i have installed fail2ban on server (os: ubuntu 16.0.4 lts). when try start it, following error message:

job fail2ban.service failed because control process exited error code. 

here outputs various diagnostic commands:

morpheous@zeus:~$ sudo systemctl status fail2ban.service ● fail2ban.service - fail2ban service    loaded: loaded (/lib/systemd/system/fail2ban.service; enabled; vendor preset: enabled)    active: inactive (dead) (result: exit-code) since sat 2016-10-29 11:46:36 utc; 18s ago      docs: man:fail2ban(1)   process: 23122 execstart=/usr/bin/fail2ban-client -x start (code=exited, status=255)  oct 29 11:46:36 zeus systemd[1]: fail2ban.service: unit entered failed state. oct 29 11:46:36 zeus systemd[1]: fail2ban.service: failed result 'exit-code'. oct 29 11:46:36 zeus systemd[1]: fail2ban.service: service hold-off time over, scheduling restart. oct 29 11:46:36 zeus systemd[1]: stopped fail2ban service. oct 29 11:46:36 zeus systemd[1]: fail2ban.service: start request repeated quickly. oct 29 11:46:36 zeus systemd[1]: failed start fail2ban service.    morpheous@zeus:~$ sudo journalctl -xe oct 29 11:46:36 zeus systemd[1]: fail2ban.service: service hold-off time over, scheduling restart. oct 29 11:46:36 zeus systemd[1]: stopped fail2ban service. -- subject: unit fail2ban.service has finished shutting down -- defined-by: systemd -- support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel --  -- unit fail2ban.service has finished shutting down. oct 29 11:46:36 zeus systemd[1]: fail2ban.service: start request repeated quickly. oct 29 11:46:36 zeus systemd[1]: failed start fail2ban service. -- subject: unit fail2ban.service has failed -- defined-by: systemd -- support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel --  -- unit fail2ban.service has failed. --  -- result failed. oct 29 11:46:55 zeus sudo[23124]: morpheous : tty=pts/0 ; pwd=/home/morpheous ; user=root ; command=/bin/systemctl status fail2ban.service oct 29 11:46:55 zeus sudo[23124]: pam_unix(sudo:session): session opened user root morpheous(uid=0) oct 29 11:46:55 zeus sudo[23124]: pam_unix(sudo:session): session closed user root oct 29 11:47:01 zeus kernel: iptables_input_denied: in=eth0 out= mac=[mac_address] src=[lan_ip_address] dst=[server_ip_address] oct 29 11:47:09 zeus sudo[23128]: morpheous : tty=pts/0 ; pwd=/home/morpheous ; user=root ; command=/bin/journalctl -xe oct 29 11:47:09 zeus sudo[23128]: pam_unix(sudo:session): session opened user root morpheous(uid=0) lines 1353-1374/1374 (end) 

does know what's going on here, , more importantly - how resolve issue?

if not wrong have not installed mta (sendmail/postfix) on server. try restart fail2ban after installing sendmail/postfix.

i have fixed issue after installing mta.