Windows & BSOD · critical

How to fixBOOTMGR-MISSING

BOOTMGR is missing

What this error means

BOOTMGR is missing (BOOTMGR-MISSING) is a critical-severity fault affecting the Windows operating system. The 'BOOTMGR is missing' error appears at startup before Windows loads. The Windows Boot Manager (BOOTMGR) is the first program loaded by UEFI/BIOS to find and launch the Windows OS loader. If BOOTMGR is missing, corrupted, or on a partition that is not marked as active/bootable, Windows cannot start at all. The steps below are ordered to resolve this efficiently.

Before you begin

Save open work and back up important files. Note any recent driver or hardware changes. If Windows cannot start, use the startup guide first.

Work through these checks

0 of 3 complete
01Boot from Windows installation USB and run Startup Repair

Boot from Windows installation USB and run Startup Repair.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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02Use bootrec /fixmbr and bootrec /fixboot

Use bootrec /fixmbr and bootrec /fixboot.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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03Verify boot drive is properly connected and detected in BIOS

Verify boot drive is properly connected and detected in BIOS.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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Possible causes

  • Corrupt MBR or Boot Sector
  • Bootable partition not marked active
  • Drive disconnected during boot