upgrading caused this error

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Could not calculate the upgrade

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

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: ubuntu-release-upgrader-core 1:17.04.10
ProcVersionSignature: Ubuntu 4.8.0-59.64-generic 4.8.17
Uname: Linux 4.8.0-59-generic i686
ApportVersion: 2.20.4-0ubuntu4.9
Architecture: i386
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Mon Jan 1 17:51:39 2018
InstallationDate: Installed on 2017-02-14 (321 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release i386 (20161012.2)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to zesty on 2018-01-02 (0 days ago)
VarLogDistupgradeTermlog:

[Ubuntu Foundations Team Bug Bot (crichton)]

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. Thanks.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1069133, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.
[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]