GNU GRUB Version 2.02 beta 2-9 while booting from USB

Solution 1:

I'll refer to that prompt as a 'grub rescue' crash. You can use the grub commands with steps provided in this answer: https://unix.stackexchange.com/a/148042/81664

I have used those steps in the past and it works. However, I usually use a different set of steps that also works. The steps below that I'm using involves updating grub and reinstalling grub.

The reinstalling will incidentally repair and problem glitches in the original install that is causing the crash. The update with find all installed OSes and add them to the boot menu.

You can most likely remedy this by manually installing grub on your desired HD.

Boot to a live try Ubuntu session, then run the following at a terminal prompt:

a) sudo mount /dev/sdaX /mnt # Make "sdaX" the partition that has Ubuntu install (i.e. /dev/sda2)
b) for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt/$i"; done
c) sudo chroot /mnt
d) update-grub
e) if no errors skip this "e" section
     grub-install /dev/sdX (sdX is the hard drive that has linux installed (i.e. /dev/sda)
     update-grub 5) Reboot the system

After you have performed the manual steps be sure to set your computer bios to have your desired boot drive as the default boot device.