Linux GRUB Rescue — Unknown Filesystem Fix

Fix "GRUB rescue>" prompt. GRUB cannot find its configuration files or the boot partition. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Error: error: unknown filesystem / GRUB rescue>. Category: Linux Boot Error. GRUB bootloader is broken. System cannot boot into Linux. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Partition table changed (Windows update, resize). GRUB files deleted or corrupted. Dual-boot Windows update overwrote bootloader. Drive order changed in BIOS. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Find correct partition: ls (hd0,gpt1)/. Set root: set root=(hd0,gpt2). Load normal mode: insmod normal → normal. After booting: sudo grub-install /dev/sda && sudo update-grub. Use a Live USB to chroot and repair GRUB. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Linux Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.