package otrs2 3.3.5-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

database upgrade of otrs2 fails every time, can't see the error, since the screen is replaced every time with the notification of error and selection (abort, retry, retry without asking)...

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: otrs2 3.3.5-1
ProcVersionSignature: Ubuntu 3.5.0-54.81~precise1-generic 3.5.7.33
Uname: Linux 3.5.0-54-generic x86_64
NonfreeKernelModules: appassure_vss
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: amd64
Date: Thu Feb 5 12:01:07 2015
DuplicateSignature: package:otrs2:3.3.5-1:subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2013-08-02 (551 days ago)
InstallationMedia: Ubuntu-Server 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130214)
PackageArchitecture: all
SourcePackage: otrs2
Title: package otrs2 3.3.5-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: Upgraded to trusty on 2015-02-05 (0 days ago)