ubuntu not being upgraded

[Tanmoy]

An unresolvable problem occurred while calculating the upgrade.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: ubuntu-release-upgrader-core 1:14.10.10
ProcVersionSignature: Ubuntu 3.16.0-43.58-generic 3.16.7-ckt13
Uname: Linux 3.16.0-43-generic x86_64
NonfreeKernelModules: sep3_15 pax
ApportVersion: 2.14.7-0ubuntu8.5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Mon Jul 13 19:18:49 2015
InstallationDate: Installed on 2014-11-23 (231 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to utopic on 2015-07-13 (0 days ago)
VarLogDistupgradeTermlog: