Fix Bootmgr Is Missing in Windows 10

This guide walks you through the most reliable ways to repair the “Bootmgr is missing” error in Windows 10. You’ll use the Windows Recovery Environment and built-in command-line tools to rebuild the boot configuration, so your PC starts normally again.

What You’ll Need

• A Windows 10 installation USB drive or recovery drive (can be created on another PC)
• Access to the BIOS/UEFI settings (usually by pressing Del, F2, F10, or Esc during startup)
• An administrator account on the PC (for command-line repairs)

Step-by-Step

1. Boot from your installation media. Insert the USB or DVD, restart the PC, and press the key shown on screen (often F12, F11, or Esc) to open the boot menu. Select your media and press Enter.
2. Open the Repair environment. When the Windows Setup screen appears, choose your language and click Next. Then click Repair your computer in the bottom-left corner.
3. Navigate to Command Prompt. In the recovery menu, go to Troubleshoot > Advanced options > Command Prompt. This opens a black window with a command line.
4. Identify your Windows drive. Type diskpart and press Enter. Then type list volume and press Enter. Look for the volume with a size that matches your Windows partition (usually the largest, often labeled “C” or with a drive letter). Note its letter (e.g., C). Type exit to leave DiskPart.
5. Run the automatic repair commands. Type the following commands one by one, pressing Enter after each, and wait for each to finish:
   bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd
6. Rebuild the BCD manually if needed. If bootrec /rebuildbcd reports an error or finds no installations, type these commands:
   ren C:\Boot\BCD BCD.old (replace C with your Windows drive letter)
   bootrec /rebuildbcd
7. Exit and restart. Type exit to close Command Prompt, then click Continue to restart Windows normally. Remove the installation media when prompted.

Common Mistakes

• Running the repair on the wrong drive letter – always verify the Windows volume letter in DiskPart before using it in commands.
• Skipping the bootrec /scanos step – it helps the tool detect your Windows installation, which is essential for a successful rebuild.
• Forgetting to remove the installation media after repair, which can cause the PC to boot from the USB again instead of the hard drive.
• Using a 32-bit recovery tool on a 64-bit system or vice versa – make sure your installation media matches your Windows architecture.

Tips

• If you have a UEFI system with GPT disks (common on Windows 10), also run bootrec /fixboot and then bcdboot C:\Windows /s S: (replace C and S with your actual drive letters) to copy boot files to the EFI partition.
• Back up your data before attempting repairs – although these commands are safe, a power failure or mistake could cause data loss.
• If you don’t have installation media, you can create a recovery drive from another Windows 10 PC by searching “Create a recovery drive” in the Start menu.
• Check your BIOS boot order – if the hard drive is not listed first, the PC might try to boot from a non-bootable device, which can show a similar error.

Troubleshooting

• If bootrec /fixboot gives “Access is denied”: This often happens on UEFI systems. Instead, use bootrec /fixmbr and then run bcdboot C:\Windows (replace C with your drive letter).
• If bootrec /rebuildbcd says “Total identified Windows installations: 0”: Your Windows partition may be hidden or not assigned a letter. In DiskPart, select the volume and run assign letter=C (or another letter), then retry the commands.
• If the error persists after all commands: The boot sector on the hard drive may be physically damaged. Run chkdsk C: /f from the Command Prompt to check for disk errors.
• If the PC still won’t boot: Try resetting your BIOS to default settings (look for “Load Optimized Defaults”) – sometimes incorrect SATA mode (IDE vs AHCI) causes boot failures.
• If you have multiple hard drives: Disconnect all but the one with Windows, then run the repair. Reconnect others after the fix.

Frequently Asked Questions

What causes the “Bootmgr is missing” error?

It usually means the Boot Manager file (bootmgr) is missing, corrupted, or the boot configuration data (BCD) is damaged. This can happen after a failed Windows update, a power outage during startup, or a disk error.

Will these steps delete my files?

No. The commands only repair boot files and the master boot record. Your personal files, apps, and settings remain untouched.

Can I fix this without a Windows installation USB?

Yes, if you have a recovery drive or a system repair disc. If not, you can create a recovery drive on another Windows 10 PC, or use the “Reset this PC” option from the recovery environment, but that may remove apps.

Why does the error appear after I changed BIOS settings?

Changing boot order, disabling legacy boot, or switching SATA mode can make the boot manager inaccessible. Revert the BIOS changes or re-enable the correct boot mode (UEFI vs Legacy).

Is this error the same as “Bootmgr is compressed”?

No, but they are similar. “Bootmgr is compressed” is usually fixed by running compact /u C:\bootmgr from the recovery Command Prompt.

How long does the repair take?

Each command usually takes less than a minute. The whole process, including booting from the USB, typically takes 10–20 minutes.

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