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.
MBR
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.

6.Select Troubleshoot.
7.Choose the Advanced options.
8.Then, go to the Command Prompt section.

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

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
C:
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.

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.
Conclusion
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!