The GRUB (Grand Unified Bootloader) is a tool for booting and loading operating system kernels, as well as the default bootloader for Linux distros-based systems. Although it is the first thing that happens when a machine boots up, regular users rarely see GRUB in action. It operates automatically and does not require any user input. When attempting to boot another operating system alongside Linux on the same machine, the bootloader of the other system may overwrite GRUB, resulting in the Linux system failing to boot. This error could be caused by an abnormal deletion of a partition containing a second/dual operating system. This article is about how to Fix GRUB Unknown Filesystem Error.
This could be a computer that was dual booting between Windows and Linux, for example. You, on the other hand, deleted the Linux partition. When you set up such a system, each partition has an MBR, which contains important information about how to boot your operating systems. After you delete the partition or OS, the MBR still has old boot sector values for either operating system and booting up may give you an error, for example, “grub rescue unknown file system”.
GRUB is a bootloader programme. It is widely used as Linux’s default bootloader. Although GRUB is commonly used in Linux, it can also boot Windows operating systems. It is extremely powerful and adaptable. The GRUB bootloader has a powerful command line interface that can be used to troubleshoot boot issues. It’s known as GRUB Rescue. Below we have mention the steps to resolve GRUB Unknown Filesystem Error.
2 Ways to Fix GRUB Unknown Filesystem Error
Enter Grub Mode
- Locate the partition where Linux will be installed and the grub directory.
- After entering rescue mode, type grub rescue > ls and press Enter on your keyboard to list all disks and partitions. For example (hd0), (hd0, msdos1), (hd0, msdos2) …
- Type grub rescue > ls (hd0) and press Enter. Repeat this step and try each partition one by one until the contents of the partition appear instead of displaying the “File system is unknown” message.
Assume that when it is (hd0, msdos8), the content appears successfully.
- Type grub rescue > set root= (hd0, msdos8) and press Enter.
- Type grub rescue > set prefix= (0,8)/boot/grub and press Enter.
- Type grub rescue > insmod normally and press Enter. Then you have now exited the grub rescue mode and entered the grub mod, which you should be familiar with.
- Type grub > normal and press Enter.
- fix grub.
- Then, you need to update the grub part of the MBR to adapt to the new partition situation, input sudo update-grub in the terminal and press Enter.
- Type sudo grub-install/dev/sda and press the Enter key. And sda is your boot disk.
Automatic Repair BCD Files Using Windows 10
- Boot your PC from the Windows 11 installation media.
- In the installation window, click on the Repair your computer option. Then select the Troubleshoot option.
- Under the advanced options, click the Command Prompt option.
- Type the following commands in Command Prompt one by one and press Enter after each one to rebuild the MBR:
- bootrec / fixmbr
- bootrec / fixboot
- bootrec / scanos
- bootrec / rebuildbcd
What is GRUB Rescue
Occasionally, while typing those grub rescue commands to boot your device, specific errors occur that impede the booting process. It’s also known as grub rescue error. This error can be caused by any disturbance to the Ubuntu partition or a misconfigured boot loader file of the operating system. This article explains every factor that contributed to the error.
When we talk about grub rescue, we’re talking about the boot loader system. This error could be caused by a misconfiguration. It may appear on the device, and you may receive a pop-up message stating that there is no such partition grub rescue while booting. When you instal grub live on the device, a portion of it is saved in Ubuntu in the Master Boot Record (MBR), while the remainder remains in the Linux boot partition. The Ubuntu component is critical.
Final Words
We hope you like our article on methods to Fix GRUB Unknown Filesystem Error will help your and resolve all your problems. This fine morning, you turned on your laptop, and Bam! A black screen will appear with the message “Unknown Filesystem” and grub rescue. If you are facing the similar issues and want to know how to resolve this problem then follow the steps mentioned above.
I hope you understand this article, How to Fix GRUB Unknown Filesystem Error.
