This is a guide on how to recover Ubuntu's GRUB Bootloader in the case of whenever a LVM UUID is changed or corrupted.

The Problem

The error "disk not found: /xxx-xxx" in grub rescue> mode suggests GRUB can't find the device or logical volume it was previously configured to boot from.

This usually happens when: * LVM volumes weren't activated during boot * The volume group UUID changed or became corrupted

The Context

The /xxx-xxx in the message is likely referring to a LVM volume by UUID, e.g.:

error: disk 'lvmid/XXX-XXX-XXX' not found

This typically means GRUB is referencing a missing or renamed LVM LV or VG

The Solution

Boot from a live ISO, open a terminal and follow these steps:

1. Check Disks and LVM State

sudo lsblk
sudo fdisk -l

Then:

sudo vgscan

This activates any found LVM volume groups and logical volumes.

Then verify with:

sudo lvdisplay

3. Mount the System Manually

Assuming your root volume is /dev/mapper/your_lvm_drive:

sudo mkdir /mnt/recovery
sudo mount /dev/mapper/your_lvm_drive /mnt/recovery

4. Prepare for chroot

sudo mount --bind /dev /mnt/recovery/dev
sudo mount --bind /proc /mnt/recovery/proc
sudo mount --bind /sys /mnt/recovery/sys
sudo chroot /mnt/recovery

The chroot command changes the root directory for the kernel, effectively making a specified directory the new starting point for any file access within the chrooted process.

5. Reinstall GRUB

grub-install /dev/sdX  # Replace sdX with the actual disk (like /dev/sda)
update-grub

Exit chroot mode, unmount the recovery path from live-boot OS and reboot the system:

exit
sudo umount -R /mnt/recovery
sudo reboot

Hope you found this article useful!