Comment 23 for bug 316872

I've run into this same problem after converting root to ext4 after a Lucid upgrade.
As soon as any files used by grub (kernels, stage1, etc) get converted to extents, grub fails.

Running grub-install from a Lucid livecd CD did not help:

mount -t ext4 /dev/sda2 /mnt
grub-install --root-directory=/mnt /dev/sda

What seems to have fixed it was to boot from a Lucid livecd and do the following:

mount -t ext4 /dev/sda2 /mnt
mount --bind /dev /mnt/dev
mount --bind /proc /mnt/proc
chroot /mnt
grub-install /dev/sda

The 'rootfstype=ext4' kernel option does not seem to be necessary.

Upgrading to grub2 is not an option for me yet because of Bug #392158.