How to repair the EFI bootloader on a GPT HDD for Windows 7, 8, 8.1 and 10 on your Dell PC


How to repair the EFI bootloader on a GPT HDD for Windows 7, 8, 8.1 and 10 on your Dell PC



This article provides information about how to resolve an issue with the EFI Bootloader not booting correctly on a GPT Hard Disk Drive. It includes instructions for various Windows Operating Systems.


Table of Contents:

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

Introduction

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

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

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


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How to repair your EFI Bootloader

Windows 7, 8, and 8.1 could install on a Legacy BIOS using MBR. However, Windows 8, 8.1, and 10 were designed to install on the UEFI BIOS using the EFI bootloader and GPT.

Note: Attempting to repair the root of a hard drive may cause you to lose any data on the drive that was not previously backed up. A best practice is to always fully back up a drive before working on it or its OS.

The GPT structure deals with many of the problems that the Bootsect command was designed to remedy in MBR. However, if you need to repair the EFI bootloader, follow the appropriate instructions below:

Windows 7

If you do have the Installation Media:

  1. Insert the Media (DVD/USB) in your PC and restart.

  2. Boot from the media.

  3. Select Repair Your Computer.

  4. Select the operating system, and click next.

  5. 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

  1. 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

  1. In order 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. Restart your PC.

  2. Tap rapidly on the <F8> key once the PC has turned on, but before the Windows Splash Screen appears.

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

  4. Select Command Prompt from the Recovery Options.

    1. Type and run the command:

      diskpart

    2. Type and run the command:

      sel disk 0

    3. Type and run the command:

      list vol

  1. 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

  1. In order 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

Windows 8 and 8.1

If you do have the Installation Media:

  1. Insert the Media (DVD/USB) in your PC and restart.

  2. Boot from the media.

  3. Select Repair Your Computer.

  4. Select Troubleshoot.

  5. 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

  1. Verify that the EFI partition (EPS - EFI System Partition) is using the FAT32 file system. Assign a drive letter to it (Assign a letter 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

  1. In order 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. Restart your PC

  2. Tap rapidly on the <F8> key once the PC has turned on, but before the Windows Splash Screen appears.

    Be aware this may take several attempts. The timing for this option was shortened significantly from that in Windows 7.

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

  4. Select Command Prompt from 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

  1. Verify that the EFI partition (EPS) is using the FAT32 file system. Assign a drive letter to it (Assign a letter 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

  1. In order 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

Windows 10

If you do have the Installation Media:

  1. Insert the Media (DVD/USB) in your PC 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

  1. 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

  1. In order 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. Restart your PC

  2. Tap rapidly on the <F8> key once the PC has turned on, but before the Windows Splash Screen appears.

    Be aware this may take several attempts. The timing for this option was shortened significantly from that in Windows 7.

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

  4. 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

  1. 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

  1. In order 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

The next step is the same across all the operating systems:

  1. Rebuild the BCD store.

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

    ren BCD BCD.old

  3. Now recreate it using this command:

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

Note: If you are creating boot entries on an attached USB Flash or other external drive, add /f between the : and the ALL. Remember that the <boot letter> is replaced with the letter of the drive that you are booting from. (e.g., C:\, D:\)


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How to repair your MBR (Master Boot Record)

These steps apply to any legacy drive used as a boot drive on any recent Windows Operating system.

  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 disc or flash drive.

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

  3. Click on 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 PC with the installation media removed to check if the repair worked

If you require further assistance, please contact Technical Support.

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Article ID: SLN300987

Last Date Modified: 09/17/2020 03:52 AM

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