GRUB Installation Failed at the Final Stage When Installing Ubuntu / Linux Mint (UEFI Fix)

Problem Description

On some motherboards, likely due to unusual or non-standard UEFI firmware behavior, installing Ubuntu Server, Ubuntu Desktop, or Linux Mint in UEFI mode may fail at the very last stage.

The installer proceeds normally until the step:

“Installing GRUB to target devices”

Then it suddenly aborts with an error message similar to:

“Sorry, there was a problem completing the installation.

Do you want to try starting the installation again?”

At this point, the installer reports a fatal error and exits.

Important Note: The System Is Usually Already Installed

If you are installing Ubuntu or Linux Mint, in most cases:

The operating system itself has already been successfully installed
Only the bootloader (GRUB) installation failed
Reinstalling the whole system is not necessary

You may safely power off the machine at this stage.

After rebooting from the internal disk, you will typically see:

A grub> promptor
A system that fails to boot entirely

This indicates a recoverable GRUB/UEFI issue, not a broken installation.

Solution: Repair GRUB from the Live USB Environment

Step 1: Boot from the Installation USB Again

Boot using the same Ubuntu / Linux Mint USB installer
Make sure you boot it in UEFI mode
Choose “Try Ubuntu” or “Try Linux Mint”
Open a terminal

Step 2: Identify Your Installed System Partitions

Run:

lsblk -f

Locate:

The Linux root partition (usually ext4, e.g. /dev/sda2)
The EFI System Partition (ESP) (vfat, ~300–550MB, e.g. /dev/sda1)

Adjust the device names in the following commands if yours are different.

Step 3: Manually Mount the Installed System

sudo mount /dev/sda2 /mnt
sudo mount /dev/sda1 /mnt/boot/efi

If you have a separate /boot partition, mount it as well.

Step 4: Bind System Directories

These bindings are required for chroot to work correctly:

sudo mount --bind /dev  /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys  /mnt/sys
sudo mount --bind /run  /mnt/run

Step 5: Enter the Installed System Environment

sudo chroot /mnt

You are now operating inside your installed system, not the live environment.

Step 6: Reinstall GRUB in UEFI Mode

For Ubuntu:

grub-install \
  --target=x86_64-efi \
  --efi-directory=/boot/efi \
  --bootloader-id=ubuntu

For Linux Mint (optional, cosmetic difference only):

grub-install \
  --target=x86_64-efi \
  --efi-directory=/boot/efi \
  --bootloader-id=linuxmint

Step 7: Regenerate GRUB Configuration

update-grub

You should see output similar to:

Found linux image…
Found initrd image…

This confirms that GRUB has detected your installed kernel correctly.

Step 8: Reboot

exit
sudo reboot

Result

Your system should now boot normally in UEFI mode.

🎉 Enjoy your working Ubuntu / Linux Mint installation!

This issue appears more frequently on systems with:

Non-standard UEFI firmware
Strict or buggy EFI implementations

Fortunately, the fix is straightforward once you know that:

A GRUB installation failure at the final step does NOT mean the OS installation failed.

Saving this knowledge can easily spare you a full reinstall.