[dist-upgrader] error upgrade 14.04.03 lts

[S A]

From upgrade manager i select upgrade to 14.04.03 LTS
it give me

Impossibile calcolare l'avanzamento

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

Se non vengono installati, segnalare il problema usando il comando «ubuntu-bug ubuntu-release-upgrader-core» in un terminale.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.19
ProcVersionSignature: Ubuntu 3.2.0-91.129-generic-pae 3.2.71
Uname: Linux 3.2.0-91-generic-pae i686
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu17.11
Architecture: i386
Date: Tue Oct 13 19:49:09 2015
GsettingsChanges: com.ubuntu.update-manager launch-time 1416778246
InstallationMedia: Ubuntu 10.04.3 LTS "Lucid Lynx" - Release i386 (20110720.1)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2015-10-13 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

Reviewing the files from your upgrade attempt you seem to have enabled a PPA that provides Xorg packages. This will prevent the upgrade as that PPA contains different versions of packages essential to Ubuntu. The page, https://launchpad.net/~xorg-edgers/+archive/ppa, contains details on to how to revert to the official Xorg packages for the xorg-edgers PPA. Instructions for reverting to official Xorg packages should be similar for the PPA that you have enabled.