Windows Boot Manager Is Missing from My BIOS or UEFI! How to Fix That?

Overview of Windows Boot Manager in BIOS and UEFI

To solve “Windows Boot Manager is missing in UEFI/BIOS” effectively, getting to know more information about the factors is necessary. So, in this part, we will discuss about Windows Boot Manager, what is Windows Boot Manager in BIOS and UEFI separately.

Part 1. What is Windows Boot Manager?

The Windows Boot Manager (BOOTMGR) is a important component developed by Microsoft for starting your computer's operating system. When you turn on your computer, the BIOS or UEFI firmware searches for the Boot Manager.

Once found, it loads the Windows kernel and initiates the boot process, using information from the Boot Configuration Data store. However, if the Boot Manager is missing or corrupted, your computer will encounter startup issues.

Although both BIOS and UEFI require bootloaders, they still have differences between them.

Part 2. What is Windows Boot Manager in BIOS

BIOS, a firmware interface used in computers for decades, initializes hardware components and provides instructions for booting the system.

In BIOS-based systems, the boot process begins with a power-on self-test to check the hardware. Once the test is completed, BIOS searches for a bootable device, typically a hard drive or external storage.

Regarding Windows in BIOS, the Windows Boot Manager is responsible for identifying the bootable device and loading the operating system into memory. It reads the master boot record (MBR) or boot sector of the active partition, which contains the necessary instructions to start the Windows OS.

Part 3. What is Windows Boot Manager in UEFI

UEFI, the successor to BIOS, offers advanced capabilities and flexibility in the boot process and has become the standard firmware for modern computers. Unlike BIOS, the boot process in UEFI begins with hardware initialization, followed by the execution of UEFI firmware itself, containing boot-related data stored in the EFI System Partition (ESP).

In UEFI systems, the Windows Boot Manager is located within the EFI System Partition. Its main role is to identify and initiate the Windows operating system. When the computer starts up, UEFI invokes bootmgfw.efi from the EFI system partition, triggering the Windows Boot Manager. This manager uses boot entries and options stored in UEFI firmware to determine the appropriate operating system to load.

Why does Windows Boot Manager is missing from my BIOS or UEFI?

The Windows Boot Manager may be missing from your BIOS or UEFI due to the following specific reasons:

Addressing these specific issues can help resolve the problem of the missing Windows Boot Manager. Now, let’s move on to the next part to fix the problem.

How to fix Windows Boot Manager is Missing from BIOS or UEFI

According to the causes, here are 4 targeted and easy-to-follow fixes. Follow them to fix “Windows Boot Manager is missing in BIOS”.

Fix 1. Update BIOS/UEFI firmware

Step 1. Identify Your Motherboard/PC Manufacturer and Model: Press the Windows key + R on your keyboard to open the Run dialog box. Now, type msinfo32 and press Enter. In the System Information window, locate "System Manufacturer" and "System Model" entries and note them down.

Step 2. Download the BIOS/UEFI Update: Visit the official website of your motherboard/PC manufacturer and find the support/downloads section. Look for the BIOS/UEFI update based on your system model and download the latest version. Ensure you have a stable power source during the update, close open applications, and temporarily disable antivirus software.

Step 3. Run the BIOS/UEFI update file (usually .exe or .iso). Follow on-screen instructions carefully and read any warnings or prompts. Do not interrupt or turn off your PC during the update.

Step 5. Reboot your PC to check if the error is resolved.

Fix 2. Rebuild Windows BCD & MBR using Command Prompt

Step 1. Insert the Windows installation media (DVD/USB) and boot from it.  Select language preferences and click "Next."

Step 2. Click "Repair your computer" > "Troubleshoot" > "Advanced options" > "Command Prompt."

Step 3. In Command Prompt, type the following commands one by one and press Enter after each:

Fix 3. Remove all external devices

Step 1. Remove any USB flash drives or external hard drives from your computer.

Step 2. Restart the computer to check if the problem persists. If the error still occurs, carefully unplug the main USB cables connected to the PC motherboard to permanently disconnect the problematic USB device.

Fix 4. Change boot order or boot device priority

Optimize your system's boot order easily with AOMEI Partition Assistant Professional. This tool includes a user-friendly "UEFI BIOS Boot Options Manager" function, making it suitable for different computer brands.

With this tool, you can change the boot order without searching for your computer's specific BIOS entry method beforehand. It allows you to adjust the boot order while your PC is running normally and even back up your current boot settings. Moreover, the program provides a comprehensive list of all boot settings and device information, enabling you to view, detect and remove unnecessary boot options effortlessly.

Step 1. Install and run this tool on another PC, and create a bootable media.

Step 2. Once you start up your computer using this USB, you can use the "UEFI BIOS Boot Options Manager" feature.

Step 3. When the new window appears, you can select a boot option and use the buttons to move it up or down to change the order in which your computer starts up.

Or you can delete the not available or unnecessary boot option.

After you finished your setting, you can click “Restart Now” to reboot PC.

Verdict

About “Windows Boot Manager is missing from my BIOS or UEFI”, this passage provides detailed introduction and causes analysis with comprehensive guidance. If you need to change boot order, it is recommended to use AOMEI Partition Assistant for energy and time saving.

This multifunctional software can also be used for many other computer issues solving as well as device management. For example, it can clone disks, rebuild MBR, allocate free space and so on. Windows Server users can turn to the Server Edition to manage their computers effectively.