Fixing "No BOOTMGR found" Message When Booting From a Second Startup

Introduction

In this article, we will discuss the "No BOOTMGR found" error message that appears during the boot process when attempting to start a secondary drive on a computer. This issue can be frustrating and may require some technical knowledge and steps to resolve. We will cover the key concepts, provide detailed context, and use subtitles using

tags to help you understand and address this problem.

Understanding the Boot Process

When a computer starts, the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface) loads the Master Boot Record (MBR) or GUID Partition Table (GPT) from the primary boot disk to begin the boot process. The MBR or GPT contains information about the location of the operating system, along with a boot loader. The boot loader then takes control and initiates the loading of the operating system.

The "No BOOTMGR found" Error Message

The "No BOOTMGR found" error message occurs when the boot loader can't find the Boot Manager (BOOTMGR) file, which is responsible for loading the operating system. This error can happen due to several reasons, such as corrupted system files, incorrect boot order in the BIOS or UEFI, or when trying to boot from a secondary drive that doesn't have a properly configured boot loader.

Steps to Fix "No BOOTMGR found" Error Message

Here are some steps to help you resolve the "No BOOTMGR found" error message when booting a secondary startup drive:

1. Check the Boot Order in BIOS or UEFI

Ensure that your secondary drive is set as the first boot device in the BIOS or UEFI. Follow these steps to check and adjust the boot order:

1. Restart the computer.
2. Press the key to enter the BIOS or UEFI settings (usually F2, F10, F12, or DEL, depending on your computer or motherboard).
3. Go to the Boot or Boot Order settings.
4. Change the boot order to make the secondary drive the first boot device.
5. Save the changes and restart the computer.

2. Repair the Boot Loader

If the boot loader is corrupted or missing, you may need to repair it using a Windows installation media or a recovery drive. Follow these steps to repair the boot loader:

1. Insert the Windows installation media or recovery drive.
2. Restart the computer and enter the BIOS or UEFI settings to adjust the boot order, making the Windows installation media or recovery drive the first boot device.
3. Press any key during the initial setup screen to boot from the Windows installation media or recovery drive.
4. In the Windows Setup, click "Next" and then click "Repair your computer".
5. Select "Troubleshoot > Advanced options > Command Prompt" to open a command prompt window.
6. Type the following commands and press Enter after each one:

       bootrec /rebuildbcd

7. Follow the on-screen instructions to complete the repair process.
8. Exit the command prompt and restart the computer.

Additional Resources

• Windows 10 Inside Out by Ed Bott, Carl Cisek, and Craig Stinson (Amazon).

• "No Boot Device Found" error when installing Windows - How to fix it" by LifeWire (lifewire.com).

• Microsoft Support - "Resolve startup issues in Windows 10" (support.microsoft.com).

In this article, we discussed the "No BOOTMGR found" error message that appears when booting a secondary startup drive. The issue can be caused by various factors, including incorrect boot order or corrupted boot loader. By checking the boot order and repairing the boot loader using a Windows installation media or recovery drive, you should be able to resolve this problem and successfully boot from your secondary drive.