update-manager can not calculate the upgrade and fails

[Richard Cullinan]

Attempting to upgrade from 10.04 LTS to 12.04.1 LTS using the update manger fails to proceed. When calculating the changes required it reports an unresolved problem:
E:Unable to correct problems, you have held broken packages

I'm only using the standard Ubuntu repositories, and can not locate the broken packages.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: update-manager 1:0.134.12.1
ProcVersionSignature: Ubuntu 2.6.32-42.95-generic 2.6.32.59+drm33.24
Uname: Linux 2.6.32-42-generic i686
Architecture: i386
Date: Sun Sep 2 20:04:50 2012
GConfNonDefault:
 /apps/update-manager/check_new_release_ignore=
 /apps/update-manager/show_details=false
 /apps/update-manager/show_versions=false
InstallationMedia: Ubuntu-Netbook 10.04 "Lucid Lynx" - Release i386 (20100429.4)
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_AU.utf8
 SHELL=/bin/bash
SourcePackage: update-manager
VarLogDistupgradeTermlog:

[Jean-Baptiste Lallement (jibel)]

Thanks for your report.

The upgrade is blocked because you're using packages from the xorg-edgers PPA. Please revert to the version of the official ubuntu repository and try again. You can use ppa-purge to help you with this.

I'm closing this report because it is not a bug in Ubuntu.