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Oprava bootování UEFI windows 10

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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 for a number of Windows Operating Systems.


Table of Contents:

  1. Introduction
  2. How to repair your EFI Bootloader

1. Introduction

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

This particular article deals with running a repair of the EFI (Extensible Firmware Interface) bootloader on a GPT (GUID (Globally Unique Identifiers) Partition Table) Hard Disk Drive.

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


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2. 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 : Any repairs done to the root of a hard drive, has the possibility that the repair may go wrong. This means you would lose any data on the drive that is not previously backed up. Best Practice is always to have performed a full backup of a drive before you work on it or it's operating system.

The GPT structure deals with a lot of the problems that the Bootsect command was designed to remedy in MBR. However if you find yourself in need of repairing the EFI bootloader, you can follow the instructions below :

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 is using the FAT32 file system and assign a drive letter to it :

    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 don't 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.

    Please 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 is using the FAT32 file system and assign a drive letter to it :

    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 at this point :

  1. Rebuild the BCD store

  2. First run the command below to backup 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. Please remember that the <boot letter> is replaced with whatever the letter of the drive you are booting from is. (ie. C:\, D:\)
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