Thanks to the release of Windows 10, the integrated boot manager also got an upgrade. With the right settings, you can now easily use different operating systems on a single device. This is advantageous if you want to access Linux or an older version of Windows at the same time, for example. You simply select the appropriate variant via the boot manager during startup. However, it is not uncommon for problems to occur within the system. So before you do a complete re-installation of Windows, we’ll show you a few steps on how you can do some edits and actually use Windows 10 to repair your boot manager or startup. Proceed with caution, because interfering in this area can change the basic structure of your computer.
You should therefore create a backup of your most important data in advance, as you should before every drastic change. This way you are on the safe side in case something goes wrong while editing or trying to repair the boot manager of Windows 10.
The Basics: What is the Windows Boot Manager?
As mentioned before, the boot manager is a utility that can invoke multiple operating systems through your BIOS. If this process does not work for you, there are some possibilities for Windows 10 to repair boot manager and startup.
The first step is to clarify which standard the partition of your data medium is subject to. Basically, modern drives with a lot of storage space have a GUID Partition Table (GPT), while the predecessor Master Boot Record (MBR) is also still widely used. If you can edit your boot manager, you can easily find out the partition style of a hard disk:
- Open the Disk Management. You can find this by right-clicking on the Start menu or via Windows logo key + X.
- Not in the list above but at the bottom of the overview on the left side there is usually the label Disk 0 or Disk 1. Select this element with a right click.
- Under Properties, you find the tab Volumes, where under Partition Style GPT or MBR is defined.
Then follow the instructions that correspond to your partition style:
Windows 10 Repair Boot Manager – Partition Table MBR
- Switch to the Advanced Startup Options of Windows 10, which you can reach by repeatedly pressing the F8 key after restarting your PC or via the settings. Use Windows logo key + I to open Update and Security, then the Recovery menu, where you click Restart Now under Advanced Startup.
- In the Advanced Options, select Troubleshooting and then find the tab Command Prompt.
- In the application with black background, you enter three commands in the following order: bootrec /fixmbr, bootrec /fixboot and bootrec /scanos. Confirm each with Enter and close the Command Prompt.
- Now you can click Shutdown PC to finish the boot manager repair for Windows 10.
Windows 10 Startup Repair – GUID Partition Table (GPT)
- Open the Windows 10 Advanced Start Options as described above and then the Command Prompt. This way you can also easily read out your Windows Key.
- Again you have to enter three commands one after the other, confirming each with Enter: diskpart, sel disk 0 and list vol.
- You should now see a list with details of each volume. Look for the volume labeled ESP and note the number (for example, volume 4).
- Next, use the sel vol 4 command, with the number varying depending on the results of the previous step.
- After you have selected the volume, assign a new letter with assign letter=K: (K can be replaced arbitrarily, but must not already be assigned).
- After confirmation you type exit.
- Still in the Command Prompt, you now enter the command cd /d K:\EFI\Microsoft\\Boot\ – where K represents the name previously chosen. Confirm every single step as usual with Enter.
- To finish the process successfully, only the command bootrec /fixboot is missing.
- Finally you can repair the Windows 10 startup by entering bcdboot c:\Windows /l en-us /s K: /f ALL (K as volume label). For safety you can save your old data with ren BCD BCD.old before.
- Done! Again you can shut down and restart your PC by clicking the Shutdown PC button.
So the Windows 10 startup repair is done and working again. Are you interested in more features of Windows 10? Take a look at our blog. There you can learn how to set up a network or clean your hard disk for free. The possibilities are numerous once you used Windows 10 to repair the boot manager.