package lightdm 1.18.3-0ubuntu1.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[Melissa Lemke]

I wasn't actively using the machine: evince, chrome, and matlab were running.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: lightdm 1.18.3-0ubuntu1.1
ProcVersionSignature: Ubuntu 4.8.0-41.44~16.04.1-generic 4.8.17
Uname: Linux 4.8.0-41-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
Date: Wed Apr 5 11:52:53 2017
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2017-03-21 (14 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.19
SourcePackage: lightdm
Title: package lightdm 1.18.3-0ubuntu1.1 failed to install/upgrade: subprocess installed post-installation 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.