How to Rebuild Windows Boot Configuration Data (BCD) (2024)

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If you see a BOOTMGR is Missing error or a similar message pretty early on in the boot process, you've got a BCD problem. This article explains how to rebuild the BCD.

How to Rebuild the BCD in Windows 11, 10, 8, 7, or Vista

Rebuilding the BCD in Windows should only take around 15 minutes:

1. On Windows 11/10/8: Start Advanced Startup Options.

   On Windows 7 or Windows Vista: Start System Recovery Options.

   

2. In Windows 11/10/8, select Troubleshoot > Advanced options.

   

3. Select the Command Prompt button to start it.

   

   Command Prompt won't start immediately. Your computer will show a "Preparing" screen for a short time while it readies the computer.

   You may need to choose your account name and enter your password to get to the Command Prompt.

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

    bootrec/rebuildbcd

   

   The bootrec command will search for Windows installations not included in the BCD and then ask you if you'd like to add one or more to it.

5. You should see one of the following messages at the command line.
   

   Option 1
   

    ScanningalldisksforWindowsinstallations.Pleasewait,sincethismaytakeawhile...SuccessfullyscannedWindowsinstallations.TotalidentifiedWindowsinstallations:0Theoperationcompletedsuccessfully.

   Option 2

    ScanningalldisksforWindowsinstallations.Pleasewait,sincethismaytakeawhile...SuccessfullyscannedWindowsinstallations.TotalidentifiedWindowsinstallations:1[1]D:\WindowsAddinstallationtobootlist?Yes/No/All:

   

   See Also

   4 Ways to Fix Bootrec /Fixboot “Access Is Denied” Error

   If you see Option 1: Move on to Step 7. This result most likely means that Windows installation data in the BCD store exists but bootrec couldn't find any additional installations of Windows on your computer to add to the BCD. That's fine; you'll just need to take a few extra steps to rebuild the BCD.

   If you see option 2: Enter Y or Yes to the Add installation to boot list? question, after which you should see The operation completed successfully, followed by a blinking cursor at the prompt. Finish up with Step 10 toward the bottom of the page.

6. Since the BCD store exists and lists a Windows installation, you'll first have to remove it manually and then try to rebuild it again. At the prompt, execute the bcdedit command as shown and then press Enter:
   

    bcdedit/exportc:\bcdbackup

   

   The bcdedit command is used here to export the BCD store as a file: bcdbackup. There's no need to specify a file extension. The command should return the following on screen, meaning the BCD export worked as expected:
   

    Theoperationcompletedsuccessfully.

7. At this point, you need to adjust several file attributes for the BCD store so you can manipulate it. At the prompt, execute the attrib command exactly like this:
   

    attribc:\boot\bcd-h-r-s

   

   What you just did with the attrib command was remove the hidden file, read-only file, and system file attributes from the file bcd. Those attributes restricted the actions you could take on the file. Now that they're gone, you can manipulate the file more freely (specifically, rename it).

8. To rename the BCD store, execute the ren command as shown:
   

    renc:\boot\bcdbcd.old

   

   Now that the BCD store is renamed, you should now be able to successfully rebuild it, as you tried to do in Step 6.

   You could delete the BCD file entirely since you're about to create a new one. However, renaming the existing BCD accomplishes the same thing since it's now unavailable to Windows, plus provides you with another layer of backup, in addition to the export you did in Step 5, if you decide to undo your actions.

9. Try rebuilding the BCD again by executing the following, followed by Enter:
   

    bootrec/rebuildbcd

   

   It should produce this in Command Prompt:
   

    ScanningalldisksforWindowsinstallations.Pleasewait,sincethismaytakeawhile...SuccessfullyscannedWindowsinstallations.TotalidentifiedWindowsinstallations:1[1]D:\WindowsAddinstallationtobootlist?Yes/No/All:

   

   This means the BCD store rebuild is progressing as expected.

10. At the Add installation to boot list? question, typeY or Yes, followed by the Enter key.

    You should see this on the screen to show that the BCD rebuild is complete:
    

     Theoperationcompletedsuccessfully.

    

11. Restart your computer. Assuming that an issue with the BCD store was the only problem, Windows should start as expected.

    Depending on how you started Advanced Startup Options or System Recovery Options, you may need to remove a disc or flash drive before restarting.

If rebuilding the BCD didn't solve the problem you were having, continue troubleshooting to fix freezing and other issues that may prevent Windows from booting normally.