On my Ubuntu 18.04.2 LTS fail2ban failed to start:
Feb 25 11:04:00 systemd[1]: Starting Fail2Ban Service...
Feb 25 11:04:00 systemd[1]: Started Fail2Ban Service.
Feb 25 11:04:00 fail2ban-server[22920]: Failed during configuration: File contains no section headers.
Feb 25 11:04:00 fail2ban-server[22920]: file: '/etc/fail2ban/filter.d/postfix-sasl.conf', line: 1
Feb 25 11:04:00 fail2ban-server[22920]: 'ignoreregex =\n'
Feb 25 11:04:00 fail2ban-server[22920]: Async configuration of server failed
Feb 25 11:04:00 systemd[1]: fail2ban.service: Main process exited, code=exited, status=255/n/a
Feb 25 11:04:00 systemd[1]: fail2ban.service: Failed with result 'exit-code'.
On my Ubuntu 18.04.2 LTS fail2ban failed to start:
Feb 25 11:04:00 systemd[1]: Starting Fail2Ban Service... Feb 25 11:04:00 systemd[1]: Started Fail2Ban Service. Feb 25 11:04:00 fail2ban-server[22920]: Failed during configuration: File contains no section headers. Feb 25 11:04:00 fail2ban-server[22920]: file: '/etc/fail2ban/filter.d/postfix-sasl.conf', line: 1 Feb 25 11:04:00 fail2ban-server[22920]: 'ignoreregex =\n' Feb 25 11:04:00 fail2ban-server[22920]: Async configuration of server failed Feb 25 11:04:00 systemd[1]: fail2ban.service: Main process exited, code=exited, status=255/n/a Feb 25 11:04:00 systemd[1]: fail2ban.service: Failed with result 'exit-code'.
This commit fixed the issue.