Windows 10 and 11 Wont Boot, How To Fix UEFI Partition

Introduction

If your Windows 10 or 11 system won't boot due to a corrupted UEFI bootloader, you can rebuild the UEFI boot partition to resolve the issue. This tutorial will guide you through the process step-by-step, ensuring you can restore your system without having to reinstall Windows.

Step 1: Backup Your Data

Before proceeding, it's critical to back up any essential data. If your system isn't booting, consider using an offline boot CD like Hiren's Boot CD to access your files.

Step 2: Create a Windows Installation USB

You will need a Windows installation USB to access recovery tools. Follow these sub-steps:

1. Obtain a USB flash drive (at least 8 GB).
2. Open your browser and search for the Media Creation Tool for your version of Windows (Windows 10 or 11).
3. Download the tool from the official Microsoft website.
4. Run the Media Creation Tool:
   • Accept the user agreement.
   • Choose "Create installation media" and click Next.
   • Select "USB flash drive" and choose your USB drive.
   • Follow subsequent prompts to complete the USB creation.

Step 3: Access Command Prompt

1. Insert the USB and boot from it. You may need to change the boot order in your BIOS settings.
2. Once the Windows Setup appears, select "Repair your computer".
3. Navigate to "Troubleshoot" and then "Command Prompt".

Step 4: Backup the Current BCD

Before making changes, back up the current Boot Configuration Data (BCD):

1. In Command Prompt, type the following command to view the current BCD:

   bcdedit
   

2. To back it up, use:

   bcdedit /export C:\bcdbackup.bak
   

Step 5: Modify the BCD

To intentionally break the bootloader (for demonstration purposes):

1. Set the boot path to an invalid location:

   bcdedit /set {bootmgr} path \win
   

2. Disable recovery:

   bcdedit /set {bootmgr} recoveryenabled No
   

Step 6: Reboot and Confirm the Issue

1. Restart the system. It should fail to boot, displaying an error message.

Step 7: Prepare the UEFI Partition

1. In Command Prompt, type:

   diskpart
   

2. List the disks with:

   list disk
   

3. Select the disk where Windows is installed (usually Disk 0):

   select disk 0
   

4. List the volumes:

   list vol
   

5. Identify the UEFI partition (typically around 100 MB, formatted as FAT32) and select it:

   select vol 1
   

6. Assign a drive letter (e.g., V):

   assign letter=V
   

Step 8: Format the UEFI Partition

1. Format the UEFI partition to FAT32:

   format V: /fs:fat32
   

Step 9: Rebuild the BCD

1. Confirm the location of the Windows installation (usually on the C drive).
2. Rebuild the BCD with:

   bcdboot C:\Windows /s V: /f UEFI
   

Step 10: Verify and Exit

1. Check the contents of the V drive to ensure the EFI files are present:

   dir V:\
   cd V:\EFI
   dir
   

Conclusion

You have successfully rebuilt the UEFI bootloader, and your system should now boot into Windows. If you encounter any issues, you can use the backup BCD to restore your previous configuration. For further maintenance, consider running a system file checker to ensure your installation is healthy.