I guess this is one of those "Nope, no-one knows" issues.

In the end I just used efibootmgr to delete the Ubuntu option and went back to booting Windows 10 all the time on that laptop.

Maybe I'll have another shot another time when I can be bothered. At least my Acer C720 is pure-Linux so I have that still.. pity suspend and resume doesn't work properly on it though :(

On Thu, 29 Oct 2015 at 14:28 Toby Corkindale <toby@dryft.net> wrote:

Hi,
After re-installing Kubuntu on my (EFI, GPT) laptop (which also has Windows 10), I've ended up with a broken grub. It used to work fine.

The problem is that now it boots into grub, with no configuration, just the grub> prompt.

I can continue by typing:
grub> configfile (hd0,gpt6)/boot/grub/grub.cfg
which then brings up the usual menu.

But I'd like to know how to configure grub so that it finds it automatically!

Needless to say, I have already tried running grub-install /dev/sda after booting.
(Which succeeds without error)

Any suggestions?

PS. I don't want to totally blank the drive, as it shares with a Windows 10 install that I'd like to keep.

Thanks
Toby