If the aim is to update older versions of Fedora to Fedora 15, then each version have to be upgraded step by step:
Upgrade Fedora 12 to Fedora 13 with Preupgrade >>
Upgrade Fedora 13 to Fedora 14 with Preupgrade >>
From Fedora 12 to Fedora 13 guide describe Preupgrade command line method. This guide works also with from Fedora 13 to Fedora 14 upgrade and from Fedora 14 to Fedora 15 upgrade.
If the Fedora version is older than Fedora 12 then I recommend Fedora 15 clean install. Also in other situations, a clean install may be sensible.
1. Upgrade Fedora 14 to Fedora 15 with Preupgrade
1.1 First start with updating all Fedora 14 packages with following command as root:
1.2 Install preupgrade as root
yum install preupgrade
1.3 Start preupgrade as root
1.4 Preupgrade information window
1.5 Choose desired release
1.6 Preparing system for upgrade
1.7 When ready to begin upgrade then reboot.
1.8 Installing Fedora 15 packages
1.9 Booting just upgraded Fedora 15 system
1.10 Fedora 15 login window
1.11 Fedora 15 desktop screenshots
Gnome 3 Shell plain
Gnome 3 Shell Activities
Gnome 3 Shell Activities Firefox running
Gnome 3 Desktop on fallback mode
2. Post-Upgrade Tasks
2.1 Remove unsupported packages
Get the list with following command:
Then remove listed packages with following command:
yum remove package1 package2 ...
2.2 Check All .rpmsave and .rpmnew Files
You find these files with following command:
find / -print | egrep "rpmnew$|rpmsave$"
Depending on the differences between original and new files. You may need to manually merge new settings from new configuration files.