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.