Upgrading ubuntu OS crashes at calculating update

Upgrading from 12.04 LTS to 14.04

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.17
ProcVersionSignature: Ubuntu 3.2.0-70.105-generic 3.2.63
Uname: Linux 3.2.0-70-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu17.7
Architecture: amd64
Date: Tue Oct 21 00:14:56 2014
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1413868423
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 604
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2014-10-21 (0 days ago)
VarLogDistupgradeTermlog: