package libpam-modules 1.3.1-5ubuntu4.3 failed to install/upgrade: pre-dependency problem - not installing libpam-modules:amd64

[Alexander Panayotov]

After upgrade from 18 LTS to 20 LTS, this started to appear

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: libpam-modules 1.3.1-5ubuntu4.3
ProcVersionSignature: Ubuntu 4.15.0-159.167-generic 4.15.18
Uname: Linux 4.15.0-159-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.20
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sat Oct 9 17:05:38 2021
ErrorMessage: pre-dependency problem - not installing libpam-modules:amd64
InstallationDate: Installed on 2017-02-12 (1699 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
Python3Details: /usr/bin/python3.8, Python 3.8.10, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: /usr/bin/python2.7, Python 2.7.18, python-is-python2, 2.7.17-4
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.6
SourcePackage: pam
Title: package libpam-modules 1.3.1-5ubuntu4.3 failed to install/upgrade: pre-dependency problem - not installing libpam-modules:amd64
UpgradeStatus: Upgraded to focal on 2021-10-09 (0 days ago)

[Steve Langasek (vorlon)]

The error in your log is:

Setting up libpam0g:amd64 (1.3.1-5ubuntu4.3) ...
Fontconfig warning: "/etc/fonts/conf.avail/53-monospace-lcd-filter.conf", line 10: Having multiple values in <test> isn't supported and may not work as expected
Gdk-ESC[1;32mMessageESC[0m: ESC[34m17:05:36.146ESC[0m: frontend: Fatal IO error 2 (No such file or directory) on X server :0.

dpkg: error processing package libpam0g:amd64 (--configure):
 installed libpam0g:amd64 package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 libpam0g:amd64

This indicates a crash in the debconf gnome frontend. This may be the result of a transient problem during the upgrade when packages are not in a consistent state.

To try to resolve the issue, you can run 'sudo dpkg --configure -a && sudo apt -f install' from a terminal.