How to Rebuild the BCD in Windows 10 or Windows 8.1

Boot Configuration Data (BCD) tells Windows Boot Manager where Windows is installed and how it should start. A damaged or missing BCD store can cause boot errors, but it is only one of several possible startup problems.

Support note: Windows 8.1 reached end of support on January 10, 2023, and Windows 10 reached end of normal support on October 14, 2025. This guide is retained for recovery of existing systems.

Start with Startup Repair

Before rebuilding BCD manually:

Enter Windows Recovery Environment (WinRE).
Select Troubleshoot > Advanced options > Startup Repair.
Let Windows diagnose the startup problem and restart.

Startup Repair can already repair common BCD and boot-record problems.

Rebuild BCD manually

If Startup Repair does not work and the symptoms still point to BCD corruption:

In WinRE, open Troubleshoot > Advanced options > Command Prompt.
Scan for Windows installations:

bootrec /scanos

Ask Bootrec to rebuild the BCD store:

bootrec /rebuildbcd

If Windows finds the expected installation, follow the prompt to add it.
Restart the PC.

Use BCDBoot when the boot files themselves need to be recreated

On Windows 10, BCDBoot can copy fresh boot-environment files from a known Windows installation.

Drive letters can change in WinRE. Confirm the drive that actually contains the Windows folder. If it is D: in WinRE, for example:

bcdboot D:\Windows

Do not assume Windows is always on C: while you are in recovery mode.

BCD is not the same as the MBR

The original version of this article treated BCD and the Master Boot Record as the same repair job. They are different components. Modern UEFI/GPT systems do not use the legacy MBR boot path in the same way as BIOS/MBR systems, so commands such as bootrec /fixmbr should not be run automatically on every machine.