Operating SystemHardware

Fixing MBR on External Drive in Windows 10: A Comprehensive Guide

MBR is the most important part of your system that allows your PC to identify the operating system’s location to let Windows 10 boot. Sometimes you may face some situations such as incorrect shutdown and viruses or other malware that can corrupt the MBR. Or, sometimes, you may receive an error that says “Bootmgr is missing”. This error will limit your device from starting. So, to fix these kinds of issues, you need to repair the MBR to allow Windows 10 to load your MBR disk again.

In this article, we described how to fix MBR on the external drive in Windows 10. To find out how to fix MBR, follow us till the end of this article.


Master Boot Record or MBR is the information in the first part of any hard drive or diskette which identifies the location of the operating system so that it can boot or be loaded into RAM or the main storage of your PC.

The MBR is also called “master partition table” or “partition sector” since it has a table consisting of each partition into which the hard disk has been formatted. Furthermore, MBR involves a program that reads the partition’s boot sector record with the OS (operating system), which needs to be loaded into RAM.

Fix MBR on Windows 10

To fix such problems that we mentioned above, follow the steps below:

1.First of all, you need to create bootable USB media on Windows 10.

2.To start from the bootable media, change the settings of the device firmware. To change the settings of BIOS (Basic Input Output System) or UEFI (Unified Extensible Firmware Interface), you need to hold one of these function keys: F1, F2, F3, F10, F12, the ESC or Delete key. But the thing is that the process varies on each manufacturer and device model. To learn more specific instructions, check your manufacturer’s support website.

3.Start your PC with bootable media.

4.Then, hit the Next button in the Windows 10 Setup.

5.Select the Repair your computer option, which is at the lower-left corner of the window.

Fix MBR on Windows 10

6.Select Troubleshoot.

7.Choose the Advanced options.

8.Then, go to the Command Prompt section.

Fix MBR on External Drive in Windows 10

9.Then, the Command Prompt window will appear. In this environment, you are allowed to launch the Bootrec.exe tool to fix the MBR on Windows 10. The Bootrec.exe command tool supports a lot of various options based on your situation.

Here is a list of some options:

  • The FixMbr option allows you to fix the Master Boot Record corruption problems. Also, it allows you to delete the code from the Master Boot Record. This command will not overwrite the table of the existing partition in the hard drive. To do so, copy and paste this command: Bootrec /fixMbr
  • It is better to use the FixBoot option when a non-standard code was placed instead of the boot sector, when the boot sector is corrupted, or when you install an early version of your OS (Operating System) instead of a more recent version. To do so, copy and paste this command: Bootrec /fixBoot
  • When you have a problem like not showing the list of all the installed OS on your device, you need to use the ScanOS option. This option will scan your drives to find all the compatible installations. It will also show the entries that are not in the BCD store. To do so, copy and paste this command: Bootrec /ScanOS
  • When you do not have any other option, and you need to rebuild the BCD (Boot Configuration Data) store, you can use the RebuildBcd option. To do so, copy and paste this command: Bootrec /RebuildBcd
Fix MBR on External Drive in Windows 10

10. Now, if rebuilding the BCD store and troubleshooting the “Bootmgr Is Missing” error did not fix the problems, you would use the following commands to erase and export the BCD store. Then, you need to use the RebuildBcd command again to fix the Windows 10 process.

Type this command while you are using the recovery environment in the Command Prompt:

BCDedit /export C:\BCD_Backup


CD boot

Attrib BCD -s -h -r

Ren C:\boot\bcd bcd.old

Bootrec /RebuildBcd

Then, hit Enter.

11. Then, to confirm adding Windows 10 to the list of the bootable operating systems on your PC, you should press the Y key.

Fix MBR on External Drive in Windows 10

12. Now, close Command Prompt.

After you have done the above steps, you need to reboot your PC. Now, your Windows 10 should load normally again.

If you are not sure what problem your PC has, you should try all the above commands to see if any of them can fix the issue.


In this article, we described how to fix your MBR in Windows 10. Hopefully, you can get rid of your MBR issues by doing these simple steps. Do you know another method to fix MBR in Windows 10? Was this article helpful to you? Share your ideas with us!

Kimia Sh

Kimia is an accomplished author and technology enthusiast with a keen interest in writing about Windows tips and tricks. Born and raised in Tehran, Iran, Kimia always had a fascination for technology and its ever-evolving capabilities. After completing her studies in Computer Science, Kimia started working in the software development industry, where she gained extensive experience and technical expertise. Her passion for writing about technology led her to create a blog focused on providing Windows users with useful tips and tricks. Kimia's blog quickly gained popularity, and she became known for her ability to communicate technical concepts in an accessible and easy-to-understand manner. Her articles are praised for their clarity and practicality, and she has developed a loyal following of readers who look to her for advice on getting the most out of their Windows systems. In addition to writing about technology, Kimia is also an accomplished software developer and has contributed to the development of numerous applications and software programs. Her technical expertise gives her a unique perspective on the challenges faced by Windows users, and she is always seeking out new ways to make their lives easier and more efficient. When she's not working on her blog or developing software, Kimia enjoys hiking, reading, and spending time with her family and friends. She is also an avid traveler and loves to explore new cultures and cuisines. Overall, Kimia is a talented author and technology expert who is passionate about sharing her knowledge with others. Her dedication to providing practical, useful advice to Windows users has made her a respected figure in the industry, and she continues to inspire and educate others through her work on her blog and beyond.

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