Sorry, I had forgotten to purge a nightly cinnamon ppa, purged and downgraded 23 packages and the upgrade is now working.
** Changed in: ubuntu-release-upgrader (Ubuntu) Status: Incomplete => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1509688 Title: failed to calculate upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1509688/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs