Fix: “error: unknown filesystem. grub rescue” in Ubuntu

Learn how to fix the “error: unknown filesystem. grub rescue” problem in Ubuntu and Linux Mint with this step-by-step tutorial.

Do you get this “error: unknown filesystem.
grub rescue>
” error message when you start your computer?

Then you've come to the right place because This tutorial will show you how to repair grub in Linux Mint and Ubuntu.

How to repair GRUB

error: unknown filesystem.
grub rescue>

1. Type the following command:


ls

2. Press the Enter key on your keyboard.

This command will show all the partitions on your hard drive.

Example 1:


grub rescue> ls (hd0) (hd0,gpt5) (hd0,gpt4) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1) (fd0) grub rescue>

Example 2:


grub rescue> ls (hd0) (hd0,msdos5) (hd0,msdos4) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1) (fd0) grub rescue>

3. Now you will need to find the partition where Linux Mint or Ubuntu is installed on. To do this, type the following command:


ls (hd0,...)

4. Press Enter.

Do this for every partition until you see something, like:


grub rescue> ls (hd0,gpt5)/./ ../ lost+found/ etc/ media/ bin/ boot/ dev/ home/ lib/ mnt/ opt/ proc/ root/ run/ sbin/ selinux/ srv/ sys/ tmp/ usr/ var/ initrd.img initrd.img.old vmlinuz cdrom/ grub rescue>

In my example is (hd0,gpt5) the correct partition and I'll be using this partition as an example in the following steps, so don't forget to replace gpt5 with your correct partition.

5. Type the following command:


set prefix=(hd0,gpt5)/boot/grub

Don't forget to replace gpt5 with your partition.

6. Press Enter.

7. Type the following command:


set root=(hd0,gpt5)

Don't forget to replace gpt5 with your partition.

8. Press Enter.

9. Type the following command:


ls /

10. Press Enter.

11. Type the following command:


insmod normal

12. Press Enter.

13. Type the following command:


normal

14. Press Enter.

The Grub will now open a boot menu and display all installed operating systems.

15. Boot into Linux Mint or Ubuntu.

16. Open a Terminal window.

17. Type the following command:


sudo update-grub

18. Press Enter.

19. Type the following command:


sudo grub-install /dev/sda

20. Press Enter.

21. Close the Terminal.

This solution fixed my problem and hopefully, it will also fix your problem.