Comment # 12 on bug 1185441 from Tiago Marques

Hi,

I've been hit by this for some months now. Every Grub2 update, I get the same
message as OP.
Not sure which grub package is to blame and I'm using EFI and secure boot.

I've managed to (twice) solve the issue by booting a live USB, chrooting and
then running 'shim-install'.

Not sure where the bug is or if this helps. I'm available to test other things
out to help fix this.