About 13 days ago or so, I posted an entry on my preparations to upgrade Fedora Workstation KDE 25 to Fedora 26.
My original intention was to do it via CLI, but it did not go well because, after having downloaded all the packages, the system reported insufficient space in / for the install. Apparently I, being a Fedora noob, had not removed all the old packages and had less than 75 MB left.
I performed a clean install and everything went perfect. I am still trying to figure out how to enable the scanner, though.
By the way, # yum clean all gets rid of the old packages.
During those days, Mageia 6 was finally released, so I decided to remove the Mageia 5 on my work laptop and put in the brand new version. I kept my /home and the upgrade was perfect.
Today I even changed the Mageia 6 Sta2 on my daughter's UEFI desktop and a problem that prevented me to install WINE there was gone.
Good!