I want to reinstall GRUB 2 and I found these instructions: How to Repair, Restore, or Reinstall Grub 2 with a Ubuntu Live CD or USB. In my case, the boot loader is installed in the EFI partition. If I use the commands provided in this guide, will GRUB be reinstalled to the EFI partition automatically, or will it be installed into the root partition where Ubuntu is installed ? Obviously, I do not want this to happen.
Reinstall the GRUB boot loader to your Ubuntu installation in EFI mode this way ...
Boot from the Ubuntu installation medium and select 'Try Ubuntu without installing'.
(Boot your install medium in EFI mode, select the Ubuntu entry with UEFI in front.)
Once you are on the Live desktop, open a terminal and execute these commands :
sudo mount /dev/sdXY /mnt sudo mount /dev/sdXX /mnt/boot/efi for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done sudo chroot /mnt grub-install /dev/sdX update-grub
sdX = disk |
sdXX = efi partition |
sdXY = system partition
To identify the partitions use GParted, the tool is included in the installation medium.
After having run the commands GRUB will be installed in the separate EFI partition.
this is the only way that worked for me: (System: sdb8, boot: sdb6, efi: sdb2)
sudo mount /dev/sdb8 /mnt sudo mount /dev/sdb6 /mnt/boot sudo mount /dev/sdb2 /mnt/boot/efi sudo mount --bind /dev /mnt/dev && sudo mount --bind /dev/pts /mnt/dev/pts && sudo mount --bind /proc /mnt/proc && sudo mount --bind /sys /mnt/sys sudo chroot /mnt grub-install --target=x86_64-efi /dev/sdb grub-install --recheck /dev/sdb exit && sudo umount /mnt/sys && sudo umount /mnt/proc && sudo umount /mnt/dev/pts && sudo umount /mnt/dev && sudo umount /mnt
Thanks to @cl-netbox for the instructions!
After I upgraded (Linux Mint 18.2 Sonya to 18.3 Sylvia) my system wouldn't boot so I followed the instructions above but still no success. I noticed however that my machine has /boot in a separate partition (possibly because I am using LVM) so my slightly modified process was:
sudo mount /dev/sdXXX /mnt sudo mount /dev/sdXY /mnt/boot sudo mount /dev/sdXX /mnt/boot/efi for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done sudo chroot /mnt grub-install /dev/sdX update-grub
Note : sdX = disk | sdXX = efi partition | sdXY = boot partition | sdXXX = system partition
This is how I did it on a standard x86_amd64 EFI desktop, without chrooting, assuming you have a partition containing Ubuntu on your hard drive and possibly an EFI partition where GRUB should be installed.
# boot on a live Ubuntu, I used 18.04 but more recent should work # if you have currently no EFI partition (maybe it was deleted, # or you are migrating to a new drive): # sudo gparted # - create a FAT 32 partition of around 100 MB on the disk of your choice # (in general the one that host the Ubuntu partition). If you plan to # move or resize some paritions, anticipate that (for instance by # creating the EFI partition at the end of the free space). # - set the flag esp on this partition (the flag boot will also be selected) # now assuming that the Ubuntu partition is `/dev/sda2` and the (possibly new) EFI partition is `/dev/sda1` sudo apt install grub-efi sudo mkdir /media/root && sudo mount /dev/sda2 /media/root sudo mkdir /media/efi && sudo mount /dev/sda1 /media/efi sudo grub-install --target=x86_64-efi /dev/sda --efi-directory=/media/efi --boot-directory=/media/root/boot
This should give:
Installing for x86_64-efi platform.
Installation finished. No error reported.
Then reboot and you should be done. You may have to tell your BIOS which drive to use, or which EFI partition to use, or which EFI binary to use.
If you created a new EFI partition, you may have to add it to
/etc/fstab to have
update-grub working correctly.
For more information : https://wiki.archlinux.org/index.php/Multiboot_USB_drive#Hybrid_UEFI_GPT_+_BIOS_GPT/MBR_boot
Also, if booting from live cd to recover it might happen that you are missing grub-efi-amd64-bin package and then line
"grub-install --target=x86_64-efi /dev/sdb"
fails with error message: "grub-install: error: /usr/lib/grub/x86_64-efi/modinfo.sh doesn't exist. Please specify --target or --directory."
In this case run this outside of chroot
sudo apt get grub-efi-amd64-bin
and then add /usr/lib/grub/x86_64-efi to chroot mounts.
BTW "/dev/sdb" param is obsolete and is being ignored.
If you happen to lose your EFI partition, it's easy to get it back. You can use a partitioning tool such as
parted to create a new partition sdXY (e.g. sda1) with type "EFI partition (1)" and format it with:
sudo mkfs.msdos /dev/sdXY
then mount it with:
sudo mount /dev/sdXY /boot/efi
and you can reinstall GRUB by running:
sudo grub-install --efi-directory=/boot/efi
as mentioned in other solutions.
in addition to ci-netbox answer.
If your pendrive OS version does not match the one that is installed on the disk, grub-install may have difficulties to identify the right grub installation:
$ sudo chroot /mnt # grub-install /dev/sdX grub-install: error: /usr/lib/grub/i386-pc/modinfo.sh doesn't exist. Please specify --target or --directory.
Try to identify manually the installation to use
# ls /usr/lib/grub/ grub-mkconfig_lib x86_64-efi x86_64-efi-signed
Then restart grub-install :
# grub-install --target=x86_64-efi /dev/sdX Installing for x86_64-efi platform. Installation finished. No error reported.