When I try to boot I get this message:

error: unknown filesystem.
grub rescue> _

results of:

grub rescue> ls

are as follows:

(hd0) (hd0,msdos5) (hd0,msdos1) (hd1) (fd0)
  • Hey I am having the same problem as you had of grub rescue how did you fixed it? can you explain me. – user2014111 May 22 '14 at 7:33
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    Honestly, user2014111, I actually had to copy the files off of the HDD, and then I re-installed the whole OS. Sorry I couldn't be of more help... -Chandler – Chandler R. May 22 '14 at 14:43
  • Possible duplicate of Grub rescue - error: unknown filesystem – karel Aug 22 '19 at 16:13

If you don't know your Ubuntu boot partition, check them one by one:

ls (hd0,msdos5)/
ls (hd0,msdos1)/

When you hit the right one, you'll get a line mentioning "lost+found" and so on.

Assuming (hd0,msdos5) is the right partition:

set root=(hd0,msdos5)
set prefix=(hd0,msdos5)/boot/grub
insmod normal

Now you'll be able to boot into Ubuntu. Once you do, reinstall GRUB:

sudo update-grub
sudo grub-install /dev/sda
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  • I ran the first two commands with (hd0,1) in place of (hd0,5) as (hd0,msdos1) was the correct partition... they produced no message so I assumed they worked, but when I ran insmod normal... it gave me this message: error: file not found. Then I ran the normal command and it rebooted to the same problem (unknown filesystem) I am running 12.04 LTS Server Version if that changes anything. Thanks again! – Chandler R. Nov 12 '13 at 16:18
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    Nevermind that. I got it fixed! Thank you so much! – Chandler R. Nov 12 '13 at 16:45
  • Ur wlcm. Plz mark as answered. – Pavel Nov 12 '13 at 18:07
  • Hi Chadler..i am getting file not found error when i type insmod normal. please help me – Ekaveera Apr 4 '14 at 6:22
  • Hey, sorry for the late response, I have not been on StackExchange in months. You, Ekaveera, may already have it fixed, but if not, I can try to help you. However, I had the same error. I believe those instructions are for an outdated version of Ubuntu. Easiest fix is to wipe the OS and then re-install. -Chandler – Chandler R. May 22 '14 at 14:46

If you have a UEFI bios make sure you boot through uefi boot and not legacy. Grub is actually there but the bios doesn't allow it to start

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The easiest way i found to fix this error was to put in an old windows 98 disk and in dos you can delete and create partitions and then format

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