Ok, I'm not the right person to judge the good quality efforts behind the Ubunt/Kubuntu update manager, but I have to say that I was never able to do a clean upgrade without any problems. The last time I upgraded my whole system I spent almost a week trying to get 3D video card acceleration back, as well as tuning again my Perl library and RT.
Sounds like it is not a well-automated upgrading...at least in my experience.

The article Ubuntu do-releease-upgrade: worst update manager ever (?) has been posted by Luca Ferrari on September 12, 2015

Tags: kubuntu