The solution to a damaged partition boot sector is to overwrite it with a new, properly configured one using the bootrec command, a relatively easy process that anyone can do. These instructions apply to Windows 11, Windows 10, Windows 8, Windows 7, and Windows Vista.

What to Know

  • Go to Advanced Startup Options or System Recovery Options, and open Command Prompt.Enter bootrec /fixboot to write a new partition boot sector to the current system partition.Remove any recovery disc or flash drive and restart your computer with Ctrl+Alt+Del or the power button.

How to Write a New Partition Boot Sector

If the partition boot sector becomes corrupted or misconfigured in some way, Windows will not be able to start properly, prompting an error like ‘BOOTMGR is missing’, very early in the boot process. When this happens, follow these steps:

  • Start Advanced Startup Options (Windows 11, 10 & 8) or System Recovery Options (Windows 7 & Vista).
  • Open Command Prompt.
  • The Command Prompt available from the ASO and System Recovery Options menus is similar to the one available from within Windows, and works very similarly between operating systems.
  • At the prompt, type the bootrec command as shown below and then press Enter.
  • bootrec /fixboot
  • This will write a new partition boot sector to the current system partition. Any configuration or corruption issues with the partition boot sector that might have existed are now corrected.
  • You should see the following message at the command line:
  • The operation completed successfully.
  • Restart your computer with Ctrl+Alt+Del or manually via the reset or power button. Depending on how you completed Step 1, you may need to remove a disc or flash drive before restarting.

Assuming that a partition boot sector issue was the only problem, Windows should start normally now. If not, continue to troubleshoot whatever specific issue you’re seeing that’s preventing Windows from booting normally.

Boot sector issues also occur in Windows XP, but the solution involves a different process.

Start Advanced Startup Options (Windows 11, 10 & 8) or System Recovery Options (Windows 7 & Vista).

Open Command Prompt.

The Command Prompt available from the ASO and System Recovery Options menus is similar to the one available from within Windows, and works very similarly between operating systems.

At the prompt, type the bootrec command as shown below and then press Enter.

bootrec /fixboot

This will write a new partition boot sector to the current system partition. Any configuration or corruption issues with the partition boot sector that might have existed are now corrected.

You should see the following message at the command line:

The operation completed successfully.

Restart your computer with Ctrl+Alt+Del or manually via the reset or power button. Depending on how you completed Step 1, you may need to remove a disc or flash drive before restarting.

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