package lightdm 1.4.0-0ubuntu2 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

[Jim Howk]

Upon boot, stuck in lightdm and/or gdm login window loop.
Login with correct password switches screen to terminal session briefly before returning to login screen.
Workaround was to switch to another screen (ctl+F5) and login using a local user/admin account and shutdown existing X11 service and then run startxfce4 from that prompt.

ProblemType: Package
DistroRelease: Ubuntu 12.10
Package: lightdm 1.4.0-0ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-44.67-generic 3.5.7.25
Uname: Linux 3.5.0-44-generic x86_64
ApportVersion: 2.6.1-0ubuntu13
Architecture: amd64
Date: Tue Dec 3 18:35:52 2013
DuplicateSignature: package:lightdm:1.4.0-0ubuntu2:subprocess installed post-removal script returned error exit status 1
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationDate: Installed on 2012-11-19 (379 days ago)
InstallationMedia: Ubuntu-Server 12.10 "Quantal Quetzal" - Release amd64 (20121017.2)
MarkForUpload: True
SourcePackage: lightdm
Title: package lightdm 1.4.0-0ubuntu2 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.