By Catherine / Last Updated April 13, 2021

About the MBR on your drive

MBR, short for Master Boot Record, a structure that will be created when you create the first partition on the hard drive for the first time. It is a very important data structure on the disk since it contains the Partition Table for the disk and a small amount of executable code for the boot start. The location is always the first sector on the disk. Without a valid MBR, it’s impossible to store data on the hard drive, let alone boot the system there.

What may cause a corrupted MBR? In fact, the MBR may be affected by malicious code, become corrupted by disk errors, or be overwritten by other boot loaders when experimenting with multiple operating systems on a host. Viruses and programs gone haywire damage MBR usually.

Corrupted MBR signs and errors

As stated before, if you got a bad MBR on a system hard drive, you may get boot failure when it is a system disk. Usually, you’ll see the following boot errors on a boot disk.

Operating System Not Found
Missing Operating System
Invalid Partition Table
......

 

If the MBR of an external hard drive is corrupted, you may encounter a problem like external hard drive not recognized. 

A damaged MBR prevents Windows from reading boot code so that the operating system cannot boot. Also, a bad data structure prevents data writing in the same way. Well, how could you fix MBR on Windows 10 or an external hard drive easily?

2 ways to repair corrupted MBR on Windows 10, 8, 7

If you get corrupted MBR on a boot disk and you have an installation disc or recovery disc in hand, you may try this way to fix it.

Way 1. Fix MBR via Windows tools

1. Shut down your PC and insert the installation disc (or similar bootable drive). Boot from that drive.

2. Select the Time, Language, Keyboard Input, and click Next. Click Repair you computer in the lower-left corner.

Repair Your Computer

3. Now, press Shift + F10 simultaneously to bring out Command Prompt. At the prompt, input the following commands successively. Each command comes with an Enter.

▪ bootrec.exe /fixmbr
▪ bootrec.exe /fixboot
▪ bootrec.exe /rebuildbcd

4. Type exit to leave the Command Prompt. Press F10 to save changes and restart your computer.

It is quite easy to fix bad MBR for system drive with the help of Windows tools. Nevertheless, most computer users do not have a bootable disc to fix MBR without Windows OS. Worse, the fixmbr command only works on boot drive, so you cannot use it on external drive. Fortunately, you have an alternative way.

Way 2. Fix MBR on Windows 10/8/7 via a powerful yet free tool

To fix MBR without bootable DVD or CD, or fix the structure on external drive and USB flash drive, you may turn to this approach.

AOMEI Partition Assistant Standard is a free yet professional hard drive manager that designs for Windows operating system only. It allows you to create a bootable USB drive (or CD) to boot up the failed computer so that you can do MBR repair in the PreOS mode using a graphical user interface.

The software supports rebuild MBR on internal/external hard drives, SSDs, portable hard drives, USB drives, etc., regardless of its brand. It also helps you easily resize C drive for better hard drive management after the repair. Windows 10/8/7/XP/Vista supported. Free download and have a try.

Download Freeware Win 10/8.1/8/7/XP
Secure Download

Fix MBR via AOMEI Partition Assistant step by step

Preparations:

1. For fixing external drive: connect the external drive to your computer. Open AOMEI Partition Assistant.

2. For fixing boot drive: Install AOMEI Partition Assistant on a healthy PC and create a bootable USB drive with it. Then, boot your own computer with the bootable USB drive. Then follow these steps.

Step 1. In AOMEI Partition Assistant Standard, right-click the disk you want to repair and select Rebuild MBR.

Rebuild System Disk MBR

Step 2. Choose a proper MBR type according to your operating system.

Choose MBR Type

Step 3. Click Apply button to execute pending operation. Wait for it to completes.

Apply

Notes:
Restart your computer if it is a boot drive.
To fix MBR on Server 2012 or other Windows Server, please turn to AOMEI Partition Assistant Server Edition.

Summary

When you get a corrupted MBR or MBR errors on your hard drive, you can refer to those two ways to get it repaired. AOMEI Partition Assistant has many features for managing hard drive partitions, such as move partition, merge partitions, copy hard drive, migrate OS to SSD, etc. If you preferring a command-line operation, please upgrade to its Professional edition.