Reviewing the files from your upgrade attempt you seem to have enabled the oibaf PPA. This will prevent the upgrade as that PPA contains different versions of packages essential to Ubuntu. Please revert to the official Xorg packages and try the upgrade again.
** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1309615 Title: trying to upgrade to xubuntu 14.04. could not calculate upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1309615/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs