cannot upgrade to 16.04 even after updating everything else

[ishan durugkar]

I updated the system using apt-get as well as the GUI.
Then tried to upgrade ubuntu from 14.04 to 16.04 multiple times.
It is having some issues

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.9
ProcVersionSignature: Ubuntu 3.13.0-121.170-generic 3.13.11-ckt39
Uname: Linux 3.13.0-121-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.14.1-0ubuntu3.24
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Tue Jun 20 11:22:10 2017
InstallationDate: Installed on 2012-04-28 (1878 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2017-06-20 (0 days ago)
VarLogDistupgradeTermlog: