How to fix boot manager failed to find OS loader

Theo Lucia

Dec 16, 2024 • Filed to: Windows Computer Solutions • Proven solutions

Whenever you boot your laptop or desktop, does it open "Startup Repair" and flashes Error code=0x490, 0x2, 0x3.which goes something as -

If you are struggling to deal with this error, then you have landed on the right page. Here we'll help you find the root cause behind this error and provide you quick solutions to fix it in Windows 7 and above.

Part 1: Reasons why the Boot Manager fails to find the OS loader?

The flashing error message tells that Startup Repair is unable to find the correct BOOTMGR bootloader at the expected location. This suggests that your desktop's bootloader is either corrupted or missing.

Here are the reasons that are responsible for the error "Boot manager failed to find OS loader"-

Reason 1: The boot volume is corrupted

If boot partition on your Windows PC corrupts, it can cause this error message to flash. The file system present on boot loader can become corrupted:

• if there is a sudden power cut or system crash
• unsafe removal of local or external drives
• unsafe shutdown
• if your computer's hard disk gets damaged physically.

Boot volume can become corrupted on both NTFS and FAT32 partitions.

Reason 2: The Bootloader has been previously deleted

The BOOTMGR file installed on your computer might get deleted due to viruses and other malware residing in your system. Any failed automatic update installation of Windows can flash error. However, it can even be due to a failed attempt at upgrading the operating system.

Windows Vista, Windows 7, 8, and 8.1—all use the new BOOTMGR bootloader.

To check if the bootloader is not deleted from your computer system, look for the BOOTMGR file in the root partition of your Windows installation drive. For Windows and Vista users it is generally the drive C:\.

For Windows 7 and above, you will find BOOTMGR located on a separate 100 MiB NTFS partition. It might be created at the beginning of your drive when you initially set up the desktop.

Reason 3: The computer's hard disk has been removed

This error can also occur if you might have removed or replaced one or more, hard disks on your computer.

Does your removed or replaced hard disk was the first boot device in the BIOS? Then probably the boot files would have been already installed to this drive.

Therefore, to avoid error it's utterly important to ensure that the boot files have already been moved to a different drive. Ensure this before you plan to replace a boot disk on your computer.

Part 2: Ways to Fix Boot Manager Failed to Find OS Loader

Here we'll provide you step-by-step basic solutions, to ensure that you can fix this error on your computers without any additional damage.

Solution 1: Use one of the Window's built-in tools—the System File Checker

You can choose to run System File Checker (SFC) to check and fix your Windows (except Vista) for any corrupt or deleted files. For this, you require a Windows Installation disk. The following steps will allow you to attempt a repair of your PC-

Step 1: Insert the installation disc of Windows into your computer's CD-ROM drive and then restart your system.

Step 2: Press key when you see this message on the screen - "Press any key to boot from CD or DVD." Choose the option - language and keyboard.

Step 3: Click the link "Repair your computer."

Step 4: Go to Troubleshoot -> Advanced options and then to Command Prompt to continue.

Step 5: Now enter the command: sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows in command line window to check for errors and tap Enter (Here C is your drive where your Windows are installed)

Step 6: Finally, reboot your system and check if the "boot manager failed to find OS loader" error has been fixed.

Solution 2: Try to fix possible bad sector or errors on the system drive

The error Boot manager failed to find OS loader can also occur if there are bad sectors on your hard drive.

Step 1: To repair any bad sectors, go to Command Prompt following steps in solution 1.

Step 2: Then enter chkdsk d: /f /r command (d: is system partition) in Command Prompt, and hit Enter to continue.

Step 3: Now reboot your computer to check if the error has been fixed.

Solution 3: Try rebuilding the BCD, MBR, and boot sector

To fix problems with the BOOTMGR bootloader, you might have to rebuild your computer's MBR (Master Boot Record), BCD (boot configuration data), and partition boot sectors.

If you have Windows installation disc, then follow below steps-

Step 1: Insert the Windows installation disc into your computer's CD-ROM drive.

Step 2: Now refer solution 1 to reach Command Prompt.

Step 3: Type below commands in the command line and tap Enter after every command-

bootrec.exe /fixmbr
bootrec.exe /fixboot
bootrec.exe /rebuildbcd

Step 4: Now reboot and check if the BCD repair tool has fixed the error.

However, if rebuilding BCD fails to address the error, you can try exporting, deleting, and running BCD again. But before entering commands you first need to ensure that BCD has been completely rebuilt. Now type below commands and tap Enter after every command-

bcdedit /export C:\BCD_Backup
c:
cd boot
attrib bcd -s -h -r
ren c:\boot\bcd bcd.old
bootrec /RebuildBcd

Reboot and check if it has fixed the error.

Part 3: How to recover data from the unbootable computer if the above methods fail?

There are times when your Windows might malfunction and all the above-mentioned solutions are tossed into the bin. Various reasons can make computers unbootable. These include overheated motherboard, a virus or malware attack, hardware-issues, BIOS settings, etc.

Download and install the data recovery software Recoverit on your system and follow the given steps-

Step 1: Select Recovery Mode

Launch Recoverit then from the given options select - "System Crash Data Recovery." Tap on "Start."

Step 2: Create Bootable Drive

Select the bootable drive USB or CD/DVD appropriately. Click "Create" and then "Format now" to confirm. For this step, you must have a back up of your data.

Do not eject your connected USB flash drive when it will now start creating a bootable drive.

Step 3: Recover data

After it has created the bootable drive, you will see three simple steps about data recovery on the screen. To adjust the boot sequence, check out how to set the computer to boot from a USB drive

Then Recoverit will launch automatically after booting from the USB drive. Choose a data recovery mode to recover your data.

Conclusion

Now you will panic a little less whenever "Boot Manager failed to find OS loader" error will flash on your screen because you now know what may have caused it. You are also now familiar with methods to fix the error. Also, if these ways fail, you are now acquainted with another method of recovering data from the unbootable computer as well.