GRUB Rescue Prompt: How to Fix Boot Errors Easily (2025-26 Guide)
- 12 October 2025
If you’ve ever started your computer and seen a black screen with the message “grub>” or “grub rescue>”, don’t panic. This message indicates that your Linux bootloader (GRUB) cannot locate the operating system or boot files.
In this complete guide, we’ll explain what the GRUB rescue prompt means, why it appears, and — most importantly — how to fix it quickly without losing data.
What Is the GRUB Rescue Prompt?
GRUB stands for GNU GRand Unified Bootloader. It’s a small program that helps your system start Linux or other operating systems installed on your computer.
When your bootloader breaks or the system can’t locate the GRUB configuration files, the GRUB rescue prompt appears.
In most cases, this message means that the GRUB configuration or boot files are missing or corrupted.
Common Message You Might See:
Minimal BASH-like line editing is supported.
For the first word, TAB lists possible command completions.
grub>
This message usually appears when the GRUB configuration or boot files are missing or corrupted.
Why Does the GRUB Rescue Prompt Appear?
There are several reasons this issue occurs. Understanding the root cause helps you apply the right fix.
1. Boot Mode Change (UEFI ↔ Legacy)
Changing your system’s boot mode between UEFI and Legacy can confuse GRUB. If Ubuntu was installed using UEFI, switching to Legacy mode breaks the boot process.
2. Partition Changes or Deletion
If you resized, reformatted, or deleted a Linux partition using tools like GParted or Windows Disk Management, GRUB might lose its boot information.
3. Reinstalling or Updating Another OS
Installing or updating Windows after installing Linux can overwrite the MBR (Master Boot Record), removing GRUB.
4. Corrupted or Missing GRUB Files
Power failures, improper shutdowns, or disk errors can damage GRUB configuration files.
5. Disk Not Detected
Sometimes, BIOS or UEFI fails to detect your main drive, especially after hardware changes or updates.
How to Fix the GRUB Rescue Prompt (Step-by-Step)
Let’s go through two proven methods—one for a temporary boot and one for a permanent fix.
Method 1: Temporary Boot from GRUB Prompt
If you want to boot your system once (without a USB stick), follow these commands at the grub> prompt:
1. Type:
ls
This lists your drives and partitions, e.g. (hd0,gpt1), (hd0,gpt2).
2. Identify your Linux partition (it usually contains /boot or /grub):
ls (hd0,gpt2)/
3. Once found, set the root and prefix:
set root=(hd0,gpt2)
set prefix=(hd0,gpt2)/boot/grub
insmod normal
normal
4. Press Enter—if all goes well, your Linux system will boot normally.
Method 2: Permanent Fix Using a Live USB (Recommended)
If you want a permanent solution:
Step 1: Boot from Ubuntu Live USB
Insert your Ubuntu installation USB
Choose Try Ubuntu without installing
Step 2: Identify Your Linux Partition
Open Terminal and run:
sudo fdisk -l
Find your Linux partition, e.g. /dev/sda2 or /dev/nvme0n1p2.
Step 3: Mount the Partition
sudo mount /dev/sda2 /mnt
Step 4: Mount Essential Directories
sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
Step 5: Chroot into the System
sudo chroot /mnt
Step 6: Reinstall GRUB
For BIOS (Legacy):
grub-install /dev/sda
For UEFI systems:
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=ubuntu
Step 7: Update GRUB and Reboot
update-grub
exit
sudo reboot
Your system should now boot perfectly without showing the rescue prompt.
Bonus Tips: Preventing GRUB Errors in the Future
To ensure you don’t face the same issue again:
Avoid switching between UEFI and Legacy modes.
Back up the GRUB configuration:
sudo cp /boot/grub/grub.cfg /boot/grub/grub.cfg.backup
Use reliable tools when managing partitions.
Keep your system updated with:
sudo apt update && sudo apt upgrade
GRUB Rescue vs. GRUB Boot Menu: What’s the Difference?
Feature | GRUB Boot Menu | GRUB Rescue Prompt |
Purpose | Allows OS selection | Emergency repair console |
Appearance | List of OS options | Black screen with command prompt |
When It Appears | During normal boot | When bootloader is broken |
How to Fix | Select OS | Run manual commands |
Transitioning between these modes is automatic based on GRUB’s state. If files are missing or misconfigured, GRUB drops to rescue mode to help you repair manually.
Buy a USB Drive for System Recovery
You can use a bootable USB to easily recover your Linux or Windows system anytime. Make sure to keep one handy — it can save you hours of troubleshooting.
Final Thoughts: Fixing GRUB Rescue Prompt Made Easy
Encountering the GRUB rescue prompt might look intimidating, but as you’ve seen, fixing it is simple once you understand the steps. Whether the issue comes from BIOS settings, disk corruption, or missing partitions, you can restore your system within minutes.
Remember — keeping backups, maintaining your partitions, and avoiding random boot mode changes will ensure you never face the problem again.
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