After using the preupgrade-cli command to upgrade from Fedora 10 to Fedora 11 on one of my servers, it would not boot. It stopped with GRUB as the only text on the screen. This usually means a problem has occurred with the boot loader during stage 1 of the GRUB boot process.
After booting into rescue mode and chroot’ing /mnt/sysimage I discovered that there was no /boot/grub/device.map file. This can be resolved by installing grub which reinstalls the master boot record ( MBR). First you must find the partition on which your /boot partition resides. You can do this with either the mount or df command which shows the mountpoints for your partitions. In my case the results showed it to be located on /dev/sda. So I ran the following command to install the MBR.
# grub-install /dev/sda
This reinstalls GRUB and creates the /boot/grub/device.map file. My newly created device.map file looks like this:
# this device map was generated by anaconda
A reboot resulted in a clean boot.
It is not clear whether this problem had anything to do with using the preupgrade process or the preupgrade-cli command specifically, or if it was simply an unexplained anomaly in the upgrade process.
After having another, similar failure on a different computer I can say that it is not a problem specific to using the preupgrade-cli command but rather an anomaly in the overall upgrade process. This time the symptom was a complete failure to boot and not even the GRUB prompt was displayed. So it looks like the boot record was wipe out but never replaced, or it was mangled during installation.
In any event using the grub-install command as shown above resolved the problem.
This particular problem also occurs occasionally when upgrading from Fedora 11 to Fedora 12.