The problem is very likely caused by xorg-edgers ppa. You can use ppa-purge to uninstall it and revert to the packages from the official repository. Then run the release upgrade again and tell if it helped.
The problem is very likely caused by xorg-edgers ppa. You can use ppa-purge to uninstall it and revert to the packages from the official repository. Then run the release upgrade again and tell if it helped.