package ppp 2.4.5-5.1ubuntu2.1 failed to install/upgrade: unable to make backup link of `./usr/share/doc/ppp/PLUGINS.gz' before installing new version: Operation not permitted

[Mig]

Unable to properly install updates whenever there are any available.

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: ppp 2.4.5-5.1ubuntu2.1
ProcVersionSignature: Ubuntu 3.13.0-58.97-generic 3.13.11-ckt22
Uname: Linux 3.13.0-58-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
Date: Thu Jul 30 18:13:48 2015
DuplicateSignature: package:ppp:2.4.5-5.1ubuntu2.1:unable to make backup link of `./usr/share/doc/ppp/PLUGINS.gz' before installing new version: Operation not permitted
ErrorMessage: unable to make backup link of `./usr/share/doc/ppp/PLUGINS.gz' before installing new version: Operation not permitted
InstallationDate: Installed on 2014-10-28 (275 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
SourcePackage: ppp
Title: package ppp 2.4.5-5.1ubuntu2.1 failed to install/upgrade: unable to make backup link of `./usr/share/doc/ppp/PLUGINS.gz' before installing new version: Operation not permitted
UpgradeStatus: No upgrade log present (probably fresh install)