Linux Boot Repair After GParted Partition Changes

fix-linux-boot-after-gparted.md

Fixing Linux Boot After Resizing or Moving Partitions with GParted

Why This Happens

When you move or resize partitions, GParted may change partition UUIDs. The bootloader (GRUB) and /etc/fstab reference partitions by UUID, so those references become invalid.

Prerequisites

• Boot from a live USB of your Linux distribution

Step 1: Identify Your Disk Layout

lsblk -o NAME,SIZE,FSTYPE,UUID,MOUNTPOINT,LABEL
sudo fdisk -l /dev/sdX   # or nvme0n1, etc.

Note the current UUIDs and identify your root partition.

Step 2: Check Boot Mode

ls /sys/firmware/efi && echo "UEFI" || echo "BIOS"

Step 3: For GPT + BIOS Only - Create BIOS Boot Partition

If you have a GPT partition table with BIOS boot, GRUB needs a small BIOS boot partition (~1-2MB):

sudo parted /dev/sdX mkpart biosboot 34s 4096s
sudo parted /dev/sdX set N bios_grub on   # N = new partition number

Step 4: Mount Root Filesystem

sudo mkdir -p /mnt/root
sudo mount /dev/sdXn /mnt/root   # your root partition

Step 5: Fix /etc/fstab

Compare UUIDs in fstab against actual UUIDs from lsblk. Update any mismatches:

cat /mnt/root/etc/fstab
sudo nano /mnt/root/etc/fstab   # fix any outdated UUIDs

Step 6: Set Up Chroot Environment

sudo mount /dev/sdXm /mnt/root/home   # if separate home partition
sudo mount --bind /dev /mnt/root/dev
sudo mount --bind /dev/pts /mnt/root/dev/pts
sudo mount --bind /proc /mnt/root/proc
sudo mount --bind /sys /mnt/root/sys
sudo mount --bind /run /mnt/root/run

Step 7: Reinstall GRUB

sudo chroot /mnt/root grub-install /dev/sdX   # disk, not partition
sudo chroot /mnt/root update-grub

Step 8: Verify and Reboot

grep "root=UUID" /mnt/root/boot/grub/grub.cfg | head -1   # verify correct UUID
sudo umount -R /mnt/root
sudo reboot

Remove live USB when prompted.