Fedora 22 to 23 upgrade
Issues:
Stale ubuntu packages created problems and were difficult to remove because one wanted to remove over 1,000 packages. The commands to fix this were lost from the history buffer.
Nvidia X11 would not start due to due to some new ABI feature. Most reliable fix seems to be to downgrade:
dnf –showduplicates –allowerasing –releasever=22 downgrade xorg-x11-server-Xorg