If you are upgrading to Fedora 31 and use KDE, just to be aware that ‘/usr/bin/startkde’ is not present in Fedora 31
This caused issues for me when trying to start X (using kdm too). The cleanest solution I could find was to do:
ln -s /usr/bin/startplasma-x11 /usr/bin/startkde
See also:
https://bugzilla.redhat.com/show_bug.cgi?id=1785826