How to Repair the EFI Bootloader on a GPT Hard Drive for Windows Operating Systems

Table of Contents:

1. Introduction
2. How to repair your EFI Bootloader
3. How to repair your Main Boot Record (MBR)

Introduction

Most people with boot issues on Windows Operating Systems choose to reinstall the operating system rather than attempt to fix the boot issue itself.

This article deals with repairing the Extensible Firmware Interface (EFI) bootloader on a GUID [Globally Unique Identifiers] Partition Table (GPT) Hard Disk Drive.

This solution only works for operating systems that are installed on a Unified Extensible Firmware Interface (UEFI) Basic Input/Output System (BIOS).

How to repair your EFI Bootloader

Windows 7 and Windows 8 are no longer supported by Microsoft and typically installed on a Legacy BIOS that used the Main Boot Record (MBR). However, Windows 11 and Windows 10 are designed to install on the UEFI BIOS using the EFI bootloader and GPT.

The GPT structure deals with many of the problems that the Bootsect command was designed to remedy in MBR. However, the following instructions take you through repairing the EFI bootloader:

Repair the EFI Bootloader in Windows 11

If you do have the Installation Media:

1. Insert the Media (DVD or USB) in your personal computer and restart.

2. Boot from the media.

3. Select Repair Your Computer.

4. Select Troubleshoot.

5. Select Advanced Options.

6. Choose Command Prompt from the menu:

   1. Type and run the command:

      diskpart

   2. Type and run the command:

      select disk 0

   3. Type and run the command:

      list vol

7. Verify that the EFI partition (EPS - EFI System Partition) is using the FAT32 file system. Assign a drive letter to it that is not already in use:

   1. Type and run the command:

      select vol <number of volume>

   2. Type and run the command:

      assign letter=<drive letter>

   3. Type and run the command:

      exit

If you do not have the Installation Media:

1. Use one of the methods in the following article to boot into the Windows Advanced Startup Options Menu:

   • Booting to the Advanced Startup Options Menu in Windows 11 and Windows 10

2. Select Repair your computer from the menu that appears.

3. Select Command Prompt from the Advanced Options tab in the Troubleshoot screen:

   1. Type and run the command:

      diskpart

   2. Type and run the command:

      select disk 0

   3. Type and run the command:

      list vol

4. Verify that the EFI partition (EPS) is using the FAT32 file system and assign a drive letter to it that is not already in use:

   1. Type and run the command:

      select vol <number of volume>

   2. Type and run the command:

      assign letter=<drive letter>

   3. Type and run the command:

      exit

5. To repair the boot record:

   1. Type and run the command:

      cd /d <drive letter>:\EFI\Microsoft\Boot\

   2. Type and run the command:

      bootrec /FixBoot

Repair EFI Bootloader in Windows 10

If you do have the Installation Media:

1. Insert the Media (DVD or USB) in your personal computer and restart.

2. Boot from the media.

3. Select Repair Your Computer.

4. Select Troubleshoot.

5. Select Advanced Options.

6. Choose Command Prompt from the menu:

   1. Type and run the command:

      diskpart

   2. Type and run the command:

      sel disk 0

   3. Type and run the command:

      list vol

7. Verify that the EFI partition (EPS - EFI System Partition) is using the FAT32 file system. Assign a drive letter to it that is not already in use.):

   1. Type and run the command:

      sel vol <number of volume>

   2. Type and run the command:

      assign letter <drive letter>:

   3. Type and run the command:

      exit

   Note: If you are running Windows 10 (version 1709 or newer), ignore step 8 and go to the information at the end of this section of instructions.

8. To repair the boot record:

   1. Type and run the command:

      cd /d <drive letter>:\EFI\Microsoft\Boot\

   2. Type and run the command:

      bootrec /FixBoot

If you do not have the Installation Media:

1. Use one of the methods in the following article to boot into the Windows Advanced Startup Options Menu:

   • Booting to the Advanced Startup Options Menu in Windows 11 and Windows 10

2. Select Repair your computer from the menu that appears.

3. Select Command Prompt from the Advanced Options tab in the Troubleshoot screen:

   1. Type and run the command:

      diskpart

   2. Type and run the command:

      sel disk 0

   3. Type and run the command:

      list vol

4. Verify that the EFI partition (EPS) is using the FAT32 file system and assign a drive letter to it that is not already in use:

   1. Type and run the command:

      sel vol <number of volume>

   2. Type and run the command:

      assign letter=<drive letter>:

   3. Type and run the command:

      exit

5. To repair the boot record:

   1. Type and run the command:

      cd /d <drive letter>:\EFI\Microsoft\Boot\

   2. Type and run the command:

      bootrec /FixBoot

Rebuild the Boot Configuration Data (BCD) store in Windows 11 and Windows 10 (Version 1709 and newer):

Rebuild the BCD store.

1. First run the command below to back up the old BCD:

   ren BCD BCD.bak

2. Now re-create it using this command:

   bcdboot c:\Windows /s <boot letter>: /f ALL (You can add a switch before /s for the computer locale: /l <language code>. By default, /l en-us English USA is used.)

3. bootrec /rebuildbcd

Rebuild the BCD store in Windows 10 (before Version 1709):

Rebuild the BCD store.

1. First run the command below to back up the old BCD:

   ren BCD BCD.old

2. Now re-create it using this command:

   bcdboot c:\Windows /l en-us /s <boot letter>: All

How to repair your Main Boot Record (MBR)

These steps apply to any legacy drive used as a boot drive on a Windows Operating System. It has been left here as a reference.

1. Use the F12 key at the Dell Splash screen to enter the boot menu. It lets you boot from the Windows installation media or a bootable disk or flash drive.

2. Click the Repair your Computer link at the bottom of the Install Now screen.

3. Click Troubleshoot.

4. Select Command Prompt

5. Enter the following three commands in turn, following each by pressing the Enter key:

   bootrec /fixmbr

   bootrec /fixboot

   bootrec /rebuildbcd

6. Restart the computer with the installation media removed to check if the repair worked.

If you require further assistance, contact Dell Technical Support.

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Recommended Articles

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• Converting your Hard Drive from MBR to GPT
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• No boot device found when you change the Boot sequence to Legacy mode
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