package fail2ban 0.9.3-1 failed to install/upgrade: η υποδιεργασία installed post-installation script επέστρεψε κατάσταση λάθους 1

[abcdefg2345]

Why doesn't this install successfully? I also have installed Dovecot, Postfix and Apache.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: fail2ban 0.9.3-1
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
AptOrdering:
 fail2ban: Install
 python3-pyinotify: Install
 fail2ban: Configure
 python3-pyinotify: Configure
 NULL: ConfigurePending
Architecture: amd64
Date: Wed Jun 8 18:55:40 2016
ErrorMessage: η υποδιεργασία installed post-installation script επέστρεψε κατάσταση λάθους 1
InstallationDate: Installed on 2013-12-20 (900 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
PackageArchitecture: all
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: fail2ban
Title: package fail2ban 0.9.3-1 failed to install/upgrade: η υποδιεργασία installed post-installation script επέστρεψε κατάσταση λάθους 1
UpgradeStatus: Upgraded to xenial on 2016-04-23 (45 days ago)

[abcdefg2345 (xinuiwu-deactivatedaccount)]

Found it. There was no sasl inside the folder "filter.d" but [sasl] was defined on /etc/fail2ban/jail.local (don't know why though...). After commenting the [sasl] section, everything works.