Fix Windows Boot Manager Missing from BIOS After Installation

If Windows installs successfully but Windows Boot Manager doesn't appear in BIOS, the EFI boot partition may be missing from your Windows drive.

This commonly happens when multiple SSDs or HDDs are connected and Windows uses an EFI partition on another drive.

Here's how to fix it without reinstalling Windows.

Step 1: Boot from Windows Installation USB

Boot from your Windows installation USB in UEFI mode.

At the Windows Setup screen, press Shift + F10 to open Command Prompt.

Step 2: Check Your Windows Disk

Run:

diskpart
list disk
select disk 0
list partition

Replace 0 with the disk number where Windows is installed.

If the disk contains a Windows primary partition but no EFI System Partition, continue.

Step 3: Create an EFI Partition

Select the Windows partition. In this example, it's Partition 2.

select partition 2
shrink desired=300 minimum=300
create partition efi size=300
format quick fs=fat32 label="System"
assign letter=S
exit

This creates a 300 MB EFI System Partition.

Warning: Verify the correct disk and partition before running these commands. If an EFI partition already exists on the target disk, don't create another one.

Step 4: Rebuild Windows Bootloader

Verify that Windows is installed on C::

dir C:\Windows

Then run:

bcdboot C:\Windows /s S: /f UEFI

Expected result:

Boot files successfully created.

If Windows is installed under another drive letter, replace C: accordingly.

Step 5: Create UEFI Fallback Boot File

Run:

mkdir S:\EFI\Boot
copy S:\EFI\Microsoft\Boot\bootmgfw.efi S:\EFI\Boot\bootx64.efi

If bootx64.efi already exists, overwrite it only if S: is the dedicated EFI partition you just created, not a shared partition used by another operating system.

This creates the standard fallback boot path that compatible UEFI firmware can use when the normal boot entry is unavailable.

Step 6: Restart

wpeutil reboot

Remove the installation USB and try booting from your SSD.

Done! In my case, Windows booted successfully after these steps without needing to reinstall the operating system.

Note: This fix is intended for UEFI/GPT installations where the target Windows disk has no EFI partition. Firmware compatibility may vary.