package lightdm 1.18.2-0ubuntu2 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[siddhant]

not able to configure lightdm

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: lightdm 1.18.2-0ubuntu2
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Wed Sep 21 19:34:28 2016
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2016-06-10 (102 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
LightdmConfig:
 [Seat:*]
 autologin-user=
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: lightdm
Title: package lightdm 1.18.2-0ubuntu2 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)