Remove USB drives and discs, check boot order in BIOS, then boot from a Windows USB → Repair your computer → Startup Repair. If that fails, run bootrec /fixmbr, bootrec /fixboot, bootrec /rebuildbcd or bcdboot C:\Windows.

What's going on

BOOTMGR loads Windows on legacy BIOS (MBR) systems. The message appears when the firmware boots a drive without a valid boot manager, such as a data disk or USB stick, or when the active partition's boot files are damaged.

How it shows up

  • Black screen: “BOOTMGR is missing. Press Ctrl+Alt+Del to restart”.

What causes it

  • Non-bootable drive first in boot order.
  • Damaged boot sector or BCD.
  • Wrong active partition.
  • Failing drive.

How to fix it, step by step

  1. Remove mediaUnplug USB drives, SD cards and discs.
  2. Check boot orderSet the Windows drive first in BIOS.
  3. Startup RepairBoot a Windows USB → Repair your computer → Troubleshoot → Startup Repair.
  4. Rebuild boot filesRun the commands below in recovery Command Prompt.
  5. Check the driveRun chkdsk C: /f and test the drive's health.

Command

bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd

Windows Recovery → Command Prompt. If /fixboot is denied on UEFI systems, use bcdboot C:\Windows instead.

How to tell it worked: The PC boots straight into Windows.

Keeping it from coming back

Don't leave USB drives connected when starting up.