Comment 3 for bug 1948895

When an additional USB Disk is not present:
grub> ls
(proc) (hd0) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1)

When an additional USB Disks is present:
grub> ls
(proc) (hd0) (hd0,gpt1) (hd1) (hd1,gpt3) (hd1,gpt2) (hd1,gpt1)

When an additional USB Disks is present, the sequence of disks changes.
But, the grub config still sets 'hd0,gpt3' as root.

EFI/ubuntu/grub.cfg:
---
            set root='hd0,gpt3'
            search --label $label --set=writable
            echo 'Loading Linux ...'
                linux /boot/vmlinuz root=LABEL=$label ro console=tty1 console=ttyS0 systemd.log_level=debug systemd.debug-shell=1
---

Have to update grub.cfg to fix the issue.