How to fix Boot BCD startup errors

If the Boot Configuration Data (BCD) store is missing, becomes corrupted, or isn’t properly configured, Windows won’t be able to start and you’ll see BOOTMGR is Missing or a similar error message pretty early on in the boot process.

Boot Configuration Data (BCD) was introduced in Windows Vista by Microsoft. It replaced the boot.ini file in Vista. The BCD stores vital boot information required to start Windows including the list of the available operating systems.

The easiest solution to a BCD issue is to simply rebuild it, which you can do automatically with the bootrec command, fully explained below. Generally speaking, it is required that you boot into the advanced startup (Windows 10 or 8.1) or system recovery options (Windows 7) and run several commands from the command prompt there.

Step by Step guide

  1. Insert the installation media into the PC. Connect the USB Flash Drive to the computer or put the DVD into the DVD drive.
  2. Find out how to access the BIOS/UEFI of the machine. This should be displayed during boot. Common keys are F1, F12 or DEL.
  3. Change the boot order so that the computer boots from the USB or DVD drive before it boots from internal hard drives.
  4. Click next on the first screen of setup. That screen should highlight the installation language and keyboard.
  5. Select Repair your computer on the next screen.
  6. When the “choose an option” menu opens, select Troubleshoot.
  7. Select Advanced options.
  8. Select Command Prompt. This opens a command prompt interface.
  9. Run the following commands one after the other:
    1. bootrec /fixmbr — This option writes a MBR to the system partition but does not overwrite the system partition in the process. It fixes MBR corruption and issues with non-standard MBR code.
    2. bootrec /fixboot — This options writes a new boot sector to the system partition. Fixes damaged boot sectors, non-standard boot sectors, and issues caused by the installation of earlier Windows operating systems (pre-Vista). Ignore any error that may come up.
    3. bootrec /rebuildbcd — This options scans all connected hard drives for Windows installations. If it finds additional installations, prompts you to add them to the BCD Store. Windows should pick up the installed operating system. Make sure you add it to the BCD store. Select (a) for all during the prompt, or add installations individually instead.
  10. Exit the command prompt window.
  11. Restart the PC to find out if the repair was successful.