error: sparse file not allowed

I have had this problem performing a fresh install of Ubuntu 11.04 Natty Narwhal, however pressing any key the system will start up.

I’m running a btrfs on / with (fake)raid1 and grub2, solved by removing line:
if [ -n ${have_grubenv} ]; then save_env recordfail; fi
from /boot/grub/grub.cfg file.