grub-probe: error: Cannot find a GRUB drive for /dev/sdb1

I got this error;

grub-probe: error: Cannot find a GRUB drive for /dev/sdb1

after adding a drive to my laptop and running

sudo /usr/sbin/grub-mkconfig

I had to add an entry for the new drive in /boot/grub/device.map

sudo vi /boot/grub/device.map

I added the second line;

(hd0) /dev/sda
(hd1) /dev/sdb

I then regenerated the grub config

sudo /usr/sbin/grub-mkconfig

Finally, I updated grub with the new config

sudo update-grub2

Note: Initially, I failed to update grub with the new config and received another error "Invalid signature" when trying to boot Windows off the second drive.