Comment 154 for bug 1274320

This was fixed in 16.04, but if you had manually modified /etc/grub.d/00_header before the upgrade, the new version will not have been installed. You may have an unmodified version in /etc/grub.d/00_header.dpkg-new. If not, run ‘apt-get download grub-common; dpkg -x grub-common_2.02~beta3-4ubuntu6_amd64.deb grub-common-extracted’ and you’ll have the unmodified version in grub-common-extracted/etc/grub.d/00_header.dpkg-new.