unable to upgrade to ubuntu LTS 14.04

[Kristof Gilleman]

upgrade from 12.04
i tried disabling all 3rd party sources & strict or multiverse, but this doesn't help

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.17
ProcVersionSignature: Ubuntu 3.2.0-67.101-generic 3.2.60
Uname: Linux 3.2.0-67-generic i686
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: i386
Date: Fri Aug 15 14:41:54 2014
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1408105559
 com.ubuntu.update-manager window-height 600
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 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 2014-08-15 (0 days ago)
VarLogDistupgradeTermlog: