Upgrade to vivid failed

[Christoph]

I am using 14.10 and wanted to upgrade to vivid.

Expectation: It works.

What I did:

Before updating I ran apt-get update and apt-get dist-upgrade --fix-missing.
Then I typed sudo do-release upgrade in terminal and after confirming that I want to disable potential 3rd party packages I get the following error message (German)

What happened: Error message

Es konnte nicht ermittelt werden, welche Systemaktualisierungen
verfügbar sind

Ein unlösbares Problem trat beim Ermitteln der Systemaktualisierung
auf.

After this, the updater does a rollback.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: ubuntu-release-upgrader-core 1:14.10.10
ProcVersionSignature: Ubuntu 3.16.0-39.53-generic 3.16.7-ckt11
Uname: Linux 3.16.0-39-generic i686
ApportVersion: 2.14.7-0ubuntu8.5
Architecture: i386
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Sat Jul 4 17:49:02 2015
InstallationDate: Installed on 2014-12-31 (185 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release i386 (20140417)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to utopic on 2015-07-04 (0 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[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 package version numbers greater than the release to which you are upgrading. You can revert the PPA by installing the ppa-purge package from the official Ubuntu archive and then running 'sudo ppa-purge oibaf'. After that you try upgrading and again and if it still fails open a new bug report. Thanks and good luck!