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Asked: 2024-09-28T15:27:31+05:30 In:

How can I resolve the “unknown filesystem” error that leads me to the GRUB rescue prompt on my Ubuntu system?

anonymous user

I’ve run into this frustrating issue with my Ubuntu system, and I’m hoping someone can help me out. So, here’s what happened: I was trying to boot up my laptop after a long day, and instead of jumping straight to the Ubuntu desktop, I ended up at the GRUB rescue prompt. To make it worse, it keeps throwing this “unknown filesystem” error at me!

I’ve done a bit of digging, but it seems like there’s no one-size-fits-all solution to this problem. It’s kind of a nightmare, honestly! I’ve seen some folks suggest checking the disk partitions and grub configuration, but I need some guidance on how to approach this without making things worse.

For context, I’m not a complete newbie, but I wouldn’t say I’m an expert either. I know my way around the terminal, so I’m willing to try some commands if I can get a bit of direction. The last thing I want is to do something that wipes out my data, which is the most critical part of this whole situation.

Has anyone dealt with this issue before? What steps should I take to get out of this GRUB rescue prompt? I heard something about using the “set” command to check disk partitions, but I’m not quite sure what to look for or how to interpret that information. Also, is there any way to fix this “unknown filesystem” error without having to reinstall Ubuntu? Because that would really be a hassle.

Any tips or commands you could share would be greatly appreciated! I just want to get my laptop back up and running. If there’s a specific checklist of things to try first, that could really help me avoid going around in circles. Thanks in advance for any help you can offer!

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    2 Answers

    1. anonymous user

      To address the issue you’re facing at the GRUB rescue prompt, first, you should check which disk partitions are available and identify the one containing your Ubuntu installation. You can use the command ls within the GRUB rescue mode to list the available partitions. Look for entries like (hd0,msdos1) or similar. After identifying the partitions, you can run ls (hd0,msdos1)/ (substituting with your partition) to see if it lists files and directories, which can help determine if it is the correct partition hosting your Ubuntu OS. If the filesystem is unknown, it may indicate corruption or the need for further investigation.

      If you’ve identified the correct partition but still face the “unknown filesystem” error, you can try the following commands to attempt a fix without reinstalling Ubuntu. First, you can set the root and prefix: set root=(hd0,msdos1) and set prefix=(hd0,msdos1)/boot/grub (again, substituting with your correct partition). Then, execute insmod normal and normal; if these commands execute successfully, it should take you to the regular GRUB menu. If this fails, consider booting from a live USB and using tools like fsck to check and repair your filesystem or reinstall GRUB from the live environment, which is usually safe for your data. Always ensure to have a backup of your essential files whenever attempting troubleshooting tasks.

    2. anonymous user

      Getting Out of GRUB Rescue

      Dealing with the GRUB rescue prompt can be really frustrating, but don’t worry! Here’s a step-by-step approach you can try:

      1. Check Current Partitions:

        First, you want to see what partitions are available. Type:

        set

        This will give you a list of available drives. Look for something like (hd0,msdos1) or (hd0,gpt1). These indicate your partitions.

      2. Identify Filesystem:

        Next, you can check the filesystems on these partitions. Run:

        ls

        This will list the files in those partitions. Try each of them out (e.g., ls (hd0,msdos1)/) and see if you can see your Ubuntu directories, like boot or grub. If you see them, that’s a good sign!

      3. Setting the Boot Partition:

        If you can find the right partition (let’s say it’s (hd0,msdos1)), set it as your root:

        set root=(hd0,msdos1)

      4. Attempt to Load GRUB:

        If you identified the right partition, you can try loading GRUB with:

        linux /vmlinuz root=/dev/sda1 (replace with your actual partition)

        initrd /initrd.img

        boot

        This attempts to boot Ubuntu directly.

      5. If All Else Fails:

        If you can’t get it to boot, it might be worth booting from an Ubuntu live USB. From there, you can check your disk using:

        sudo fsck /dev/sda1 (adjust with your partition name).

        This command checks the filesystem for errors and attempts to fix them. Also, you can reinstall GRUB with:

        sudo grub-install /dev/sda

        and then sudo update-grub.

      Whatever you do, be careful and make sure your data is backed up if you can access it. Good luck!

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