GRUB2 Rescue Mode “error: unknown filesystem”

I’ve recently added a second disk to my server, created a single partition /dev/sdb1 and put a ReiserFS filesystem on it. After system reboot I was presented with the grub rescue shell. 

Grub Rescue Shell

That was a bit unexpected, as no GRUB2 related changes were made on the /dev/sda disk that day.

GRUB loading.
Welcome to GRUB!

error: unknown filesystem
Entering rescue mode...

If you get a rescue shell, this usually means that GRUB2 failed to load the “normal” module. Live CDs are good, but a rescue shell is sometimes all we need. Sometimes.

Let’s see what disks and partitions are accessible:

grub rescue> ls

Since I have just one partition created on the new disk, it must be (hd0,msdos1).

In this case hd1 should be my primary disk. Having figured out that, the rest becomes more of less straightforward. My /boot partition is on (hd1,1), and / is on (hd1,2). Other partitions include /var and swap.

Let’s check if kernel and initrd images are visible:

grub rescue> ls (hd1,1)/
./ ../ lost+found/ config-3.2.0-4-686-pae grub/ vmlinuz-3.2.0-4-686-pae initrd.img-3.2.0-4-686-pae

Set prefix and root to the correct values and load linux module:

grub rescue> set prefix=(hd1,1)/grub
grub rescue> set root=(hd1,2)
grub rescue> insmod (hd1,1)/grub/linux.mod
grub rescue> normal

Once booted into the OS, I mounted my /boot partition and re-installed GRUB2:

# grub-install /dev/sda
# update-grub

However, after system reboot I was returned to the same rescue grub shell with “unknown filesystem”.


It turned out to be a BIOS boot order setting, which was set to boot from the second disk. Having changed the boot order in BIOS, the problem disappeared.

Note to myself: drive ordering in an operating system may not be the same as the boot drive ordering used by a firmware.

66 thoughts on “GRUB2 Rescue Mode “error: unknown filesystem”

  1. I have fedora and Windows 7 what to do ib grub rescue it is showing :-

      Grub loading
    Welcome to GRUB!
    Error:unknown filesystem
    entering rescue mode...
    Grub rescue >

    And I followed the same steps given by you but I doesnt shows:-

    Error: hd1 cannot get C/H/S values.
    Grub rescue >
  2. Hey guys I have a little problems.
    First of all sorry for my bad english. And it’s first one. :D
    Lets begin. I had two OS on my laptop /Lenovo G580/ Ubuntu 14.04 and Kali Linux 1.0.8.
    I formatted all sectors were located Ubuntu /in NTFS/.
    My grub was on Ubuntu.
    So…when i reboot laptop i saw the next sentence:

    "error: unknown filesystem
    Entering rescue mode..."
    ls output;
    "(hd0) (hd0,msdos6) (hd0,msdos5) (hd0,msdos4) (hd0,msdos3) (hd0,msdos2)"
    set output:

    I tried to change grub direction to Kali linux file, but it does not work.
    Help me.

  3. not any hd partition works visible….every partition shows “UNKNOWN FILESYSTEM” please tell me what to do now

    • What happens when you try to use the grub rescue mode? Are you able to see your disks and partitions? Can you post the output of ls?

    • hey tom I am also facing same problem .i have installed Ubuntu and windows 8.1….all things were working well last night but today I got this error …have done nothing ;(

      out put is:
      when I presspower button
      error:unknown filesystem
      Entering rescue mode…
      grub rescue > _(and when I type ls)
      (hd0) (hd0,msdos5) (hd0, msdos3) (hdo,msdos2) (hdo, msdos1)
      and grub rescue > ls (hd0)/
      error: unknown filesystem.
      same error with other commands (I installed Ubuntu on same hard drive by formatting a drive partition to Ubuntu related filesystem means not ntfs etc) so help plz what to do now

    • Hey, did you get the solution to this. I have Kali Linux and Windows 8.1. I formatted the drive for Kali Linux and now I am getting the same error as yours.

  4. Boa noite,
    erro: unknown fillesystem.
    Entering rescue mode…
    grub rescue> ls
    (hd0) (hd0,msdos6) (hd0,msdos5) (hd0,msdos3) (hd0,msdos2) hd0,msdos1)
    grub rescue> set
    grub rescue

  5. salut;
    error: unknown filesystem debian
    grub rescue> set prefix=(hd0,msdos8)/grub
    grub rescue> set root=(hd0,msdos5)
    grub rescue> insmod (hd0,msdos8)/grub/linux.mod
    error:file not found
    comment faire

  6. Ubuntu 14.04
    error: unknown filesystem
    Entering rescue mode…
    Grub rescue>

    When i do
    grub rescue> ls
    Grub rescue> (hd0) (hd0,msdos1)
    grub rescue> ls (hd1,1)/
    grub rescue> hd1 cannot get C/H/S values.

    Please help me with this.

  7. GRUB loading.

    error: unknown filesystem.
    Entering rescue mode….
    grub rescue>ls
    grub rescue>(hd0) (hd0,msdos5) (hd0,msdos2) (hd0,msdos1) (hd1) (hd1,msdos1)

    I tried root,prefix command for all partition (hd0,msdos5) (hd0,msdos2) (hd0,msdos1) (hd1,msdos1)
    I still get
    error:unknown filesystem

    Pls provide me solution ..


  8. i have the same problem:
    have a grub rescue> prompt.. ls
    (hd0) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1)
    when i do ls for each, i get “error: unknown filesystem”
    i am running a single boot ubuntu 14.04LTS on a macbook pro.

    thanks for any help that you can provide

    • You’re using GPT, so try the following:

      set prefix="(hd0,gpt1)/boot/grub"
      insmod part_gpt
      insmod linux
      insmod initrd
    • Hey, did you get the solution to this. I have Kali Linux and Windows 8.1. I formatted the drive for Kali Linux and now I am getting the same error as yours.

  9. I have same Problem. Unknown filesystem Entering rescue mode.. ls (hd0) (hd0,msdos5) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1) (hd1) please help me

  10. Hello
    I had 2 os.. Windows 7and boss linux. I had removed boss now i cannot on my aksing me the grub rescue command..whatever i give i shows me the unknown filesystem pls help ls

  11. i give ls (hd0,msdos1)
    unknown file system i check all that all could be unknown file system
    what can i do plzz help

  12. Hello. How to solve= error no such partition problem pls?

  13. Set is cmdpath=(hd0)

    Pls help me to solve the peoblm. Even i could not reinstall another software.

  14. grub rescue> all partion unknow filesystem

    ls (hd0,msdos6) (hd0,msdos5) (hd0,msdos3) (hd0, msdos2) (hd0, msdos1)

    all f partion unknown file system..

    what can i do..

  15. I configure partition and when reboot it shows the following:
    no such partition
    entering rescue mode..
    grub rescue>ls
    (hd0) (hd0,msdos5) (hd0,msdos1)
    grub rescue>ls (hd0)
    (hd0) : File system unknown
    grub rescue>ls (hd0,msdos5)
    (hd0,msdos5) : File system unknown
    grub rescue>ls (hd0,msdos1)
    (hd0,msdos5) : File system unknown

    Is there a solution here that I can do on grub rescue? or should I need to reinstall the Ubuntu OS?

  16. Running single OS, MX18 on Sony Vaio, assist button works, I can go to BIOS. I was repartitioning my main disk in GParted, I and I set two partitions to the “boot” flag. After rebooting, I’m getting the grub rescue mode.
    grub rescue> ls
    (hd0) (hd0,msdos2) (hd0,msdos1)
    Ls command for each one of above shows “Filesystem is unknown”.
    Please advice on how to proceed.

  17. Hey guys
    I have a problem.
    grub rescue> ls
    (hd0) (hd0,msdos5) (hd0,msdos1) (fd0)
    grub rescue> set root=(hd0,msdos5)
    grub rescue> set prefix=(hd0,msdos5)/boot/grub
    grub rescue> insmod normal
    error: unknown filesystem

    grub rescue> set root=(hd0,msdos1)
    grub rescue> set prefix=(hd0,msdos1)/boot/grub
    grub rescue> insmod normal
    error: unknown filesystem

  18. Ive had the same problem and fixed it using a live cd. I could see my ubuntu installed partition using lsblk, but the booted OS wouldn’t use it. Here’s the solution that worked for me:

    -Booted from Ubuntu Live CD

    -Opened terminal and tried to mount my ubuntu partition manually. Got error: “wrong fs type, bad option, bad superblock”

    -Run fsck and say yes to everything

    Try to mount it again. Should work. Also gpared won’t show errors with it anymore. Reboot and done.

    Additional info: You gotta make a mount folder for mounting, need root rights, etc. I used a Ubuntu 15 cd to repair Ubuntu 14.

  19. Hi Tomas
    Actually I tried to delete my Ubuntu partition in my dual boot os and after restarting the system what I found:
    error: unknown filesystem
    Entering rescue mode….
    grub rescue>
    I can find my drive partitions using ‘ls’ command
    But when I try to check all hd0 files it always shows “filesystem is unknown”
    Plz help me in it

  20. Hey Tomas!

    In grub rescue mode, I typed ls command and it shows four partiton.
    Then, I tried every signal partition with ls…./, But everyone shows the same answer ” unknown filesystem”

    I also tried with ‘set’

    but won’t work. Actually, I don’t which partition has linux so that I checked everyone but found nothing.

    Please help me. Thanks in advance.


  21. I had windows 10 and Kali Linux installed on my Samsung lap top,deleted the partition for Linux and now all I see is unknown filesystem,
    Grub rescue>
    ls will bring;(hd0) (hd1) (hd1,gpt9)….(hd1,gpt1) and (cd0)
    I am trying to boot from USB,but the system won’t go into bios mode and pressing F10 is showing boot menu with just ‘Kali” please I need help.

  22. In my HP Notebook I have installed Fedora and removed Windows 10 after 1 month suddenly these error occur
    error: ../../grub-core/keen/fs.c:120: unknown file system
    Entering Rescue Mode……….
    I have tried (hd0,msdos2) and (hd0,msdos1)
    Shows unknown file system

  23. Tried to upgrade ubuntu 14.04 lts. Had windows 10 running on same partition. During ubuntu upgrade, system asked for restart and since then stuck up in grub rescue mode.
    ls gives unknown file system for except hd0,6 where it gives error: bad file name.
    ls (hd0,6)/ gives
    ./ ../ lost+found/ etc/ media/ bin/ boot/ dev/ home/ lib/ lib64/ mnt/ opt/ proc/ root/ run/ sbin/ srv/ sys/ tmp/ usr/ var/ vmlinuz initrd.img cdrom/ initrd.img.old vmlinuz.old

    Please, please…help…I need to get my laptop up and running ASAP.

    • Hi, it looks like your data is still on the hard drive which is good.

      I’d suggest to get a new hard drive and install Ubuntu on it, then attach the one that’s broken and copy your data. This would be the safest way forward.

  24. OS Guest: Parrot Linux
    OS Host: macOS high Sierra 10.13

    unknown file system on all the partitions and that is the same for all my virtual machines
    is there is a solution ?

  25. my result of ls is (hd0) (hd0,msdos2) (hd0,msdos1)
    and it says all the file system is unknown.

    please help

  26. nice artical
    i can boot in fine ,but something keeps messing with my system i hit the power at the wall when this happens
    this mostly can revert you back before changes took place ,backwards and forwards we go
    any ways my problem is first tab that shows the hard drive the cd rom and file system all says they are unknown
    permissions canot be determind
    talking of permissions i have some crazy crazy permisions in propeties one that comes to mind is
    no list create/acess, its driving me nusts but there are many extra permissions that should not be there

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