5 Methods to Fix Error Loading Operating System in Windows 10, 8, 7

The problem

“Hello, experts there! Recently, whenever I try to boot my Windows 10 computer, it says "Error loading operating system" on a black screen after the computer is powered on. I am worried about whether there is something wrong with my computer. What do you know about such problem? How can I fix this issue in Windows 10? Thanks for any suggestion!”

Most computer users might have met this irritating problem when starting Windows 7, Windows 8/8.1, and Windows 10. To find out the most suitable fix, it is necessary to learn the possible culprits.

What causes "Error Loading Operating System"?

As we all know, when a computer powers on and starts up, its BIOS and CMOS will check the system setup, hard drives, and then boot the operating system. If something goes wrong during the process, the operating system won’t be launched successfully. Besides the physical damage of hard drive, the following causes can also make your Windows not to load successfully:

▸The hard drive’s system partition is damaged.

▸Computer hard disk MBR information is not right.

▸The operating system’s files and folders are damaged.

▸The system BIOS does not support the hard drive.

▸Multiple hard drives have been connected to your computer, then the computer cannot detect which one is the primary hard drive containing the operating system & system applications.

▸Some bad sectors on the system hard drive.

5 Solutions to “Error loading operating system” in Windows 10/8/7

No matter what makes your computer pop out the boot error message, below are several methods through which you can fix this annoying issue with ease.

NOTE: all the following methods operations are carried out in Windows 10 as an example.

Method 1. Check the boot order

First of all, we had better ensure the boot order is correct especially when there are several hard drives on your computer. If a wrong hard drive is set as the first boot disk, the “Error loading operating system” will absolutely appear in Windows 10/8/7. To check the BIOS boot order, take the below steps:

Step 1. Restart your computer and constantly press a specific key (usually F1, F2, F10, Delete, Esc) to enter BIOS setup menu.

Step 2. Use the arrow keys to select the Boot tab. You will see the system devices in order of priority.

Step 3. If the system disk is not in the first place in the boot order, you can move it to the top of the list of hard drives.

Step 4. Save and exit the BIOS setup utility.

If the boot order is right, you can proceed to the following methods.

Method 2. Rebuild the MBR directly without using CD

Since most computer users don’t have an original installation disc and want to know how to fix error losing operating system without CD, here we will explain how to do it in detail. This method requires a FREE disk manager: AOMEI Partition Assistant Standard, which allows you to create a bootable USB and then rebuild MBR directly without using the installation CD.

Step 1. Connect an empty USB (over 8GB) to a working Windows 10 computer (since your Windows cannot boot). Then download the freeware.

Step 2. Install and run AOMEI Partition Assistant Standard. Click on the Make Bootable Media from the "Tools" in the top toolbar. Follow the wizard to create a WinPE bootable USB disk. Disconnect the USB drive after it is done. (The bootable USB will contain installed AOMEI Partition Assistant.)

Step 3. Plug the bootable USB into the computer with boot issue. Boot it from the USB by changing boot order in BIOS.

Step 4. Once logged in, the AOMEI Partition Assistant Standard will load and start automatically. In the main interface, right click the system disk and select “Rebuild MBR”.

Step 5. In the pop-out mini window, choose the proper MBR type for Windows 10 and click “OK”.

Step 6. Click “Apply->Proceed” in the main interface to commit the change.

This method could also apply to fix MBR for Windows 10/8/8.1/XP/Vista. If you meet a similar issue in Server like Windows Server 2012 boot BCD error, you can try AOMEI Partition Assistant Server Edition.

If you have the Windows installation disk in hand, you can try the following three methods.

Method 3. Perform Startup repair

Here is how to perform Startup Repair in Windows 10:

Step 1. Insert your Windows 10 install disc into your computer and boot from it.

Step 2. Choose the language and keyboard layout you prefer and click “Next”

Step 3. Click “Repair your computer” on the bottom left corner of the screen.

Step 4. When asked what option you prefer, choose “Troubleshoot”.

Step 5. On the “Advanced options” screen, tap “Startup Repair”.

Method 4. Check hard disk status

If you are unable to perform a startup repair or stuck in the startup repair loop, then your next option is to run CHKDSK to check whether the system hard disk is in a healthy condition.

Step 1. Insert the original Windows disc, restart your computer and boot from the disk.

Step 2. At the Windows 10 Welcome screen, click "Repair your computer-> Troubleshoot->Advanced Options->Command Prompt".

Step 3. When the Command Prompt window appears, type the command: chkdsk c: /f /r /x and press Enter. (c represents the drive where Windows operating system is installed)

Or you can run AOMEI Partition Assistant under WinPE mode like you do in method 2 to check hard drive for errors and fix them.

Step 1. Right click the system partition and select “Advanced”> “Check Partition”.

Step 2. Here, select the first method to both check and fix errors in this selected partition. And click “OK”.

Besides, you can make a disk surface test to make whether there are some bad sectors on the system disk.

Method 5. Restore the MBR information of hard disk

First, open a Command Prompt window as you do in method 4 and then in the window, input the following commands and press Enter after each to fix MBR in Windows 10.

▪ bootrec /FixMbr
▪ bootrec /FixBoot
▪ bootrec /ScanOs
▪ bootrec /RebuildBcd

Then, exit Command Prompt and restart your computer.

Conclusion

So do not feel depressing any more when you encounter the “Error loading operating system” in Windows 10/8/7. Refer to this article to find the actual reasons behind this issue and try the solutions above to fix it with ease. To better deal with such similar OS boot issues, it is a great idea to clone Windows system to SSD or HDD for a backup.