package lightdm 1.8.4-0ubuntu1 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

[M. Walter]

The power supply on my CPU went bad. when I replaced it and first booted, everything looked fine, and I would get the login screen. In a few minutes the screen would go blank. If I quickly logged in, the same thing would happen. After a few minutes the screen would go blank. This is likely unrelated to my power supply.

I apt-get --purge remove lightdm and then reinstalled it. When I logged in, I got "System program problem detected." It complained about apport and then went through this debug process.

ProblemType: Package
DistroRelease: Ubuntu 13.10
Package: lightdm 1.8.4-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-13.20-generic 3.11.6
Uname: Linux 3.11.0-13-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12.5-0ubuntu2.1
AptOrdering:
 ubuntu-desktop: Purge
 lightdm-remote-session-uccsconfigure: Purge
 lightdm: Purge
 lightdm-remote-session-freerdp: Purge
Architecture: amd64
Date: Fri Nov 8 10:51:50 2013
DuplicateSignature: package:lightdm:1.8.4-0ubuntu1:subprocess installed post-removal script returned error exit status 1
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationDate: Installed on 2012-11-07 (365 days ago)
InstallationMedia: Ubuntu-Server 12.10 "Quantal Quetzal" - Release amd64 (20121017.2)
LightdmConfig:
 [SeatDefaults]
 user-session=ubuntu
 greeter-session=unity-greeter
MarkForUpload: True
SourcePackage: lightdm
Title: package lightdm 1.8.4-0ubuntu1 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: Upgraded to saucy on 2013-10-23 (15 days ago)

[Greg Sanders (greg-t)]

I get caught in this loop now and then. It happens to my laptop when I have a set of Logitech USB headphones and a second display hooked up via HDMI. If I remove those, it boots normally.

This time I discovered it happened to both lightdm and gdm. Up to today, I thought it was lightdm related.

[Greg Sanders (greg-t)]

To clarify: it's a Logitech headset (with microphone) connected by USB and a secondary display connected by HDMI.

The laptop boots normally until it reaches the login screen. I enter my password, the screen changes, blips, then I'm back at the login screen again. This cycle repeats as long as I'm willing to type in my password and hit enter.

This last time I dropped to shell (ctrl-alt-f1) and removed lightdm.

I did fail to stop it, however, and that caused "post-removal script returned error exit status 1" because it couldn't remove the user 'lightdm' (it was still in use in the other terminal). This is related to user error.

The real problem that created this scenario seems to exist somewhere else. For that problem, I was able to boot normally by removing the HDMI jack and the USB jack from my laptop.

Dunno if any of that helps anyone, but I hope so.