The easiest way is to submit another bug report and let us look at the log files. I'd guess it is cinnamon though.
https://bugs.launchpad.net/ubuntu/+source/ubuntu-release- upgrader/+bug/1279762 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1307193 Title: Failure on upgrade to 14.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1307193/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
