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FileRisk: Do not touch
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bootmgr C:\bootmgr

Windows Boot Manager for BIOS systems: a critical file, essential to startup, located at the root of the system partition.

Updated on By AltF4 Formation

What it’s for

bootmgr is the Windows Boot Manager for machines that start in BIOS (MBR) mode. The boot sector of the active partition loads it; it reads the Boot Configuration Data (BCD) store, shows the operating system menu when needed, then starts the Windows loader (winload).

What it contains

  • A small protected executable (system, hidden, read-only attributes) at the root of the active system partition.
  • It is on C: only when C: is the system partition. Otherwise it sits on a System Reserved partition that File Explorer does not show.
  • On a computer that starts in UEFI mode (the normal case for Windows 11), the equivalent is \EFI\Microsoft\Boot\bootmgfw.efi on the EFI System Partition (ESP), not C:\bootmgr. That is why Windows 11 is not in this page’s version list.
  • The BCD store and its resources are in the Boot folder of the system partition; the reference copies are in C:\Windows\Boot.

Neighboring file: BOOTNXT

At the root of the same partition you sometimes find BOOTNXT, a small hidden system file, sometimes empty, created along with bootmgr and the Boot folder. Its exact role is not publicly described. Do not read, delete or rename it, and leave it in your system images with the rest of the boot partition. On a UEFI machine, its absence is normal.

Risks and best practices

  • Without bootmgr the machine shows “BOOTMGR is missing” and will not start. Leave these files alone.
  • To repair, boot into the Windows Recovery Environment (WinRE): bcdboot C:\Windows recreates the boot files from the installed system.
  • Before touching partitions, export the BCD with bcdedit /export. You restore it with bcdedit /import.

Useful commands

Fenêtre de terminal
# File presence and attributes (hidden); BOOTNXT if present
Get-Item C:\bootmgr, C:\BOOTNXT -Force -ErrorAction SilentlyContinue | Select-Object FullName, Length, Attributes, LastWriteTime


# As administrator: boot manager configuration
bcdedit /enum '{bootmgr}'


# Back up the BCD before partition work
bcdedit /export C:\bcd-backup


# Identify the system partition
Get-Partition | Where-Object IsSystem | Select-Object DiskNumber, PartitionNumber, Type, Size

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