I received free CDs of Ubuntu Breezy Badger 5.10 recently. So I wanted to upgrade from Ubuntu Hoary Hedgehog 5.04 to the new version. After reading many posts on Ubuntuforums I decided not to do an "upgrade" but go for a new install of Breezy.
When you do a fresh install you need to reformat the partition. So how about your /home folder (containing personal files)? It is best to have /home on separate partition. If you don't have it create it, mount it and copy the required files or everything on /home.
Since I started my Linux journey with Mandriva my /home already existed on separate partition (Mandriva does it by default). When I installed Ubuntu 5.04 I used it during the installation.
I put the install CD and installed Breezy on the partition which had Hoary. I created the same userid (which I had on Hoary) and I could login to Breezy without any problem.
But I realised very soon that there was some mistake. After posting on Ubuntuforums and reading a couple of posts I found the problem. My /home contained the config files (in hidden folders/files) from Hoary and Breezy was trying to use them.
I did a fresh install after deleting most of the hidden folders/files. Before deleting .mozilla I saved my bookmarks. I did not delete .evolution (mail client) and .gaim (Instant Messenger) which were suppossed to work (and they did).
That is how I upgraded my Ubuntu Linux to the new version.