package update-notifier-common 3.168.3 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[Laurie]

I was installing updates for adapta theme and Flashplayer installer this morning when the error occurred. I'm running Ubuntu Gnome 16.04.2 LTS. I expected the updates to install without incident, however instead, I received this error.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: update-notifier-common 3.168.3
ProcVersionSignature: Ubuntu 4.4.0-67.88-generic 4.4.49
Uname: Linux 4.4.0-67-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
AptOrdering:
 adapta-gtk-theme: Install
 flashplugin-installer: Install
 adapta-gtk-theme: Configure
 flashplugin-installer: Configure
 NULL: ConfigurePending
Architecture: amd64
Date: Wed Mar 15 08:08:10 2017
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2015-08-11 (582 days ago)
InstallationMedia: Ubuntu-GNOME 15.04 "Vivid Vervet" - Release amd64 (20150422)
PackageArchitecture: all
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.20
SourcePackage: update-notifier
Title: package update-notifier-common 3.168.3 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)