package postgresql-9.5 9.5.6-0ubuntu0.16.04 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

i just using this in my rails project and when i deployed it on heroku and creating PostgreSQL db it giving me this error

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: postgresql-9.5 9.5.6-0ubuntu0.16.04
ProcVersionSignature: Ubuntu 4.4.0-66.87-generic 4.4.44
Uname: Linux 4.4.0-66-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.4
AptOrdering:
 postgresql-contrib-9.5: Purge
 postgresql-9.5: Purge
 NULL: ConfigurePending
Architecture: amd64
Date: Sat Mar 11 03:42:00 2017
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationDate: Installed on 2016-10-11 (150 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.15ubuntu0.2
SourcePackage: postgresql-9.5
Title: package postgresql-9.5 9.5.6-0ubuntu0.16.04 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)