package libpam-modules 1.1.8-1ubuntu2 failed to install/upgrade: ErrorMessage: pre-dependency problem - not installing libpam-modules:i386

[Xavier Robin]

libpam-modules failed to upgrade to trusty due to dependencies not met during the GUI upgrade process.

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: libpam-modules 1.1.8-1ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-34.60-generic 3.13.11.4
Uname: Linux 3.13.0-34-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.3
Architecture: amd64
Date: Sun Aug 17 22:14:37 2014
DuplicateSignature: package:libpam-modules:1.1.8-1ubuntu2:ErrorMessage: pre-dependency problem - not installing libpam-modules:i386
ErrorMessage: ErrorMessage: pre-dependency problem - not installing libpam-modules:i386
InstallationDate: Installed on 2012-08-03 (744 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
SourcePackage: pam
Title: package libpam-modules 1.1.8-1ubuntu2 failed to install/upgrade: ErrorMessage: pre-dependency problem - not installing libpam-modules:i386
UpgradeStatus: Upgraded to trusty on 2014-08-17 (0 days ago)

[Steve Langasek (vorlon)]

The error in your log is:

Setting up libpam0g:amd64 (1.1.8-1ubuntu2) ...
Can't load '/opt/perl/lib/x86_64-linux-gnu-thread-multi/auto/List/Util/Util.so' for module List::Util: /opt/perl/lib/x86_64-linux-gnu-thread-multi/auto/List/Util/Util.so: undefined symbol: Perl_gv_init at /opt/perl/lib/x86_64-linux-gnu-thread-multi/XSLoader.pm line 71.
 at /opt/perl/lib/x86_64-linux-gnu-thread-multi/List/Util.pm line 21.
Compilation failed in require at /opt/perl/lib/x86_64-linux-gnu-thread-multi/Scalar/Util.pm line 11.
Compilation failed in require at /usr/lib/perl/5.18/Hash/Util.pm line 9.
BEGIN failed--compilation aborted at /usr/lib/perl/5.18/Hash/Util.pm line 9.
Compilation failed in require at /opt/perl/lib/fields.pm line 123.
Compilation failed in require at /usr/share/perl5/Debconf/Log.pm line 10.
Compilation failed in require at /usr/share/perl5/Debconf/Db.pm line 7.
BEGIN failed--compilation aborted at /usr/share/perl5/Debconf/Db.pm line 7.
Compilation failed in require at /usr/share/debconf/frontend line 6.
BEGIN failed--compilation aborted at /usr/share/debconf/frontend line 6.
dpkg: error processing package libpam0g:amd64 (--configure):
 subprocess installed post-installation script returned error exit status 255
Setting up libpam0g:i386 (1.1.8-1ubuntu2) ...

You have a corrupted install, with a non-Ubuntu-provided perl polluting your environment. You will need to clear /opt/perl out of your path to be able to upgrade.