Upgrade to Fedora Core 5
I decided to upgrade from Fedora Core 4 to 5. After downloading the ISO and burning it to DVD, I made a full backup and booted the DVD to upgrade.
Most of the upgrade went fairly smoothly. The only real nuisance was that Fedora Core 5 includes version 8.1.3 of the PostgresQL databse, which can’t read the database format used by PostgreSQL 8.0.7 in Fedora Core 4.
The Fedora release notes do mention this, although they can be interpreted to imply that you can convert your data after you upgrade. This isn’t the case, so I installed PostgresQL 8.0.7 from source, exported the data, reinstalled 8.1.3 and imported the data.
That sorted everything out.