cannot update from 14.10 to 15.04

[Zakaria malha]

hardware : dell latitude E4300
current version : ubuntu 14.10
software center 13.10
problem : cannot update to 15.04 due to unkown error, i rebooted, tried on another internet connection.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: ubuntu-release-upgrader-core 1:14.10.10
ProcVersionSignature: Ubuntu 3.16.0-34.47-generic 3.16.7-ckt8
Uname: Linux 3.16.0-34-generic i686
ApportVersion: 2.14.7-0ubuntu8.4
Architecture: i386
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Sun Apr 26 01:54:34 2015
InstallationDate: Installed on 2014-12-22 (124 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release i386 (20141022.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to utopic on 2015-04-26 (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.