cannot upgrade from 13.10 to 14.04

[ElDorado18]

Tried to upgrade from 13.10 to 14.04 however after 5 mins or so it reports the following error:

Could not calculate the upgrade

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

Restarting, and re-initiating the process does not resolve the issue

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: ubuntu-release-upgrader-core 1:0.205.6
ProcVersionSignature: Ubuntu 3.11.0-20.34-generic 3.11.10.6
Uname: Linux 3.11.0-20-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
CrashDB: ubuntu
Date: Tue Apr 22 11:53:23 2014
InstallationDate: Installed on 2014-03-11 (41 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to saucy on 2014-04-22 (0 days ago)
VarLogDistupgradeTermlog: