In general, the following info was helpful regarding the use of Fedora preupgrade to go from F11 to F13:
Here's what I did (thanks to Fernando (nando@ccrma) for some extra tips):
yum update yum install preupgrade yum clean all
locate '.rpmnew' > rpmnew-2010-06-19.txt locate '.rpmsave' > rpmsave-2010-06-19.txt ;; NOTE - ONLY '/' PROCESSED BELOW (mounted drives left alone): find / -xdev -name \*.rpmnew' -exec /bin/mv {} /mnt/sda/rpmsave-rpmnew \; find / -xdev -name \*.rpmsave' -exec /bin/mv {} /mnt/sda/rpmsave-rpmnew \;
preupgrade
package-cleanup --problems package-cleanup --orphans
I have heard that I might need to try yum downgrade if the new system turns out to have an older version of some package than the previous system. (Apparently this can happen.)