How to Fix "Windows 10 Grub Rescue" Error: A Complete Guide

The Grub Rescue error in Windows 10 typically occurs when the boot loader of a dual-boot system becomes corrupted or missing, especially if you've been using Linux alongside Windows. Grub (GRand Unified Bootloader) is a Linux bootloader, and if it can't find the necessary files to boot, it throws you into a rescue mode. If you're encountering this issue on Windows 10, don’t worry - this guide will help you troubleshoot and fix the problem.

How Can I Fix Windows 10 Grub Rescue Errors?​

1. Identify the Issue in Grub Rescue Mode​

Before you proceed with fixing the problem, it's helpful to understand what is causing the issue.

1. Check for the Grub Error:
   • When you boot your system, you may see something like error: no such partition or grub rescue>.
2. Run Grub Commands:
   • At the grub rescue> prompt, type the following commands:
     • ls
   • This will list the partitions on your system. You will see something like (hd0,msdos1), (hd0,msdos2), etc.
   • Identify the partition that contains your boot files by typing:
     • ls (hd0,msdos1)/
   • Keep checking each partition until you find the one that contains /boot/grub or /boot/vmlinuz.

Identifying the correct partition where Grub is installed helps you understand where the issue lies.

2. Set the Boot Partition Temporarily​

Once you’ve found the correct partition, you can set it temporarily to boot your system.

1. Set the Root Partition:
   • At the grub rescue> prompt, type:
     arduino
     Copy code
     set root=(hd0,msdosX)
     Replace X with the correct partition number you identified earlier.
2. Load the Normal Boot:
   • Then, type the following commands to load the normal boot configuration:
     css
     Copy code
     insmod normal
     normal
3. Boot the System:
   • If successful, your system should boot into your Linux distribution or the Grub boot menu, allowing you to choose Windows 10.

This is a temporary fix to get you back into your system.

3. Fix Grub Permanently from Linux (if dual-booting)​

Once you've booted into Linux, you can reinstall or repair Grub to avoid future rescue mode issues.

1. Open Terminal:
   • Once in Linux, open a terminal window.
2. Reinstall Grub:
   • Enter the following commands to reinstall Grub to the master boot record (MBR):
     bash
     Copy code
     sudo grub-install /dev/sda
     sudo update-grub
3. Restart the System:
   • Reboot your computer. Grub should now load correctly, and you should be able to select both Linux and Windows 10 at startup.

Reinstalling Grub ensures that the bootloader is correctly set up and that future errors won’t occur.

4. Fix the Boot Loader via Windows 10 (Without Linux)​

If you’ve removed Linux or no longer need Grub, you can use the Windows boot loader instead.

Method 1: Use Windows Installation Media​

1. Create a Bootable USB:
   • Download the Windows 10 ISO and create a bootable USB using tools like Rufus.
2. Boot from the USB:
   • Insert the USB, restart your computer, and boot from the USB drive.
3. Open Command Prompt:
   • Once in the Windows setup screen, click Repair your computer.
   • Go to Troubleshoot > Advanced options > Command Prompt.
4. Repair the Boot Loader:
   • In the Command Prompt, type the following commands one by one:
     bash
     Copy code
     bootrec /fixmbr
     bootrec /fixboot
     bootrec /scanos
     bootrec /rebuildbcd
   • These commands will repair the Master Boot Record (MBR) and rebuild the boot configuration data (BCD).
5. Restart Your Computer:
   • After running the commands, restart your computer without the USB drive. Windows 10 should now boot directly.

Repairing the boot loader via the Windows installation media removes Grub and restores the Windows boot manager.

Method 2: Use Windows Automatic Repair​

If you don’t have installation media or want a quicker method, you can use Windows' built-in automatic repair tool.

1. Restart your PC a few times during the boot sequence.
2. From the list of options, Select Troubleshoot > Advanced options > Startup Repair.
3. The repair process will now start.
4. After the repair process is complete, check if the problem is resolved.

You can also use a bootable Windows 10 DVD or USB flash drive to restore the boot sector code.

1. Connect the Windows 10 bootable media to your computer (DVD or USB flash drive)
2. Restart your computer to enter into ‘Automatic Repair’ mode.
3. Go to Troubleshoot > Advanced Options > Command Prompt to launch the CMD.
4. In the CMD window, type the following command and hit “Enter” afterward:
   • diskpart
   • select disk 0
   • list volume
5. All volumes will be displayed. In the “Type” column, you will find the “DVD-ROM” value. (ensure you remember the drive letter of the Windows 10 bootable media you plugged to your PC). For instance letter E.
6. Now, type the following command and hit Enter afterward:
   • Exit
   • E:
   • cd boot
   • Dir
7. Check to see if you have bootsect.exe files in the list. If yes, enter the following command keys and hit ‘Enter’ afterward:
   • bootsect /nt60 SYS /mbr
   • Exit
8. Restart your PC and check to see if the problem is resolved.

5. Use a Third-Party Boot Repair Tool​

If you're uncomfortable using the command line, there are third-party tools that can help repair boot loader issues.

1. Download a Boot Repair Tool:
   • One popular tool is Boot-Repair, which is typically used for Linux systems but can also help with fixing Grub issues.
   • You can create a Boot-Repair live USB and boot from it.
2. Repair Grub:
   • Once booted into the Boot-Repair tool, follow the on-screen instructions to repair the Grub loader or install the Windows boot loader.

Using a third-party tool can simplify the repair process, especially for users unfamiliar with command-line commands.

6. Perform a System Restore (If Applicable)​

If the issue started after a recent change, such as a system update or software installation, you can use System Restore to revert your system to a previous state.

1. Access System Restore:
   • Boot into the Windows Recovery Environment by using installation media or the Automatic Repair screen.
2. Choose a Restore Point:
   • Select Troubleshoot > Advanced options > System Restore.
   • Choose a restore point from before the Grub error started.
3. Restore Your System:
   • Follow the on-screen instructions to complete the restoration.

System Restore can revert any changes that may have caused the Grub loader issues.

​

The Grub Rescue error in Windows 10 can be frustrating, but it’s fixable with the right tools and methods. Whether you choose to repair Grub using Linux, switch to the Windows boot loader, or use third-party tools, this guide provides multiple solutions to help you get back into your system. If the problem persists after trying these steps, it may be worth seeking professional assistance or contacting your system manufacturer.