Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

Repair the GRUB from live CD or USB stick

  1. Insert the bootable device and boot into Try Ubuntu mode

  2. Find out you root partition by typing: sudo fdisk -l or sudo blkid

  3. Mount you main partition: sudo mount [/dev/sda2] /mnt

Note: If you have separate partitions for /boo, /var and /usr, repeat steps 2 and 3 to mount them to /mnt/boot, /mnt/var and /mnt/usr respectively

  1. Bind-mount pseudo-filesystems: for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt/"$i"; done

Note: A bind mount is an alternate view of a directory tree. Classically, mounting creates a view of a storage device as a directory tree. A bind mount instead takes an existing directory tree and replicates it under a different point. The directories and files in the bind mount are the same as the original.

  1. If Ubuntu was installed in EFI mode, use sudo fdisk -l | grep -i efi to find your EFI partition and then mount it: sudo mount [/dev/sda1] /mnt/boot/efi

  2. sudo chroot /mnt

  3. update-grub

If this doesnt’t fix the GRUB, go on:

  1. grub-install /dev/sda; update-grub

  2. I fthe EFI partition ha changed, you may need to update it in /etc/fstab accordingly

  3. sudo reboot

  4. At this point, you should be able to boot normally (remember to unplug the bootable media).