How to fix 'An operating system not found' error on Windows 10 and Windows 8.1
The " An operating system not found" error is a common one that usually happens on Windows 10 or Windows 8.1. This error occurs after the user upgrades Windows (from Windows 8.1 to Windows 10), updates the BIOS, . If the screen of your Windows 10 or Windows 8.1 computer displays a message "An operating system wasn Try finding disconnected any drives that do not contain the operating system. Press Ctrl + Alt + Del to restart " , follow the steps below to fix the error.
1. Use Windows' Startup Repair tool
1. Insert Windows Boot Media into your computer and start the computer from there.
2. On the first setup screen, select Language, time and currency format and Keyboard input, then click Next.
3. On the next window, select Repair your computer.
4. Next click on Troubleshoot => Advanced options => Startup Repair.
5. Wait for Windows to find and fix the error.
6. After the Startup Repair is complete, proceed to restart your Windows computer.
2. Configure and repair boot files (boot files)
1. Insert Windows Boot Media into your computer and start the computer from there.
2. On the first setup screen, select Language, time and currency format and Keyboard input, then click Next.
3. In the next window, press Shift + F10 key combination to open the Command Prompt window.
4. On the Command Prompt window, enter the following command and press Enter to open the DISKPART utility:
diskpart
5. Enter the following command into Command Prompt and press Enter to check if your drive is set to GPT or MBR partition:
list disk
At GPT column, you find:
- If you see the sign icon (*), it means that the Partition Table of the drive is GPT.
- If you don't see the sign icon (*), the drive's Partition Table is MBR.
6. Enter Exit in the Command Prompt window and press Enter.
7. If the partition is MRB, follow the steps below:
Part 1: Fix boot file error (boot file) on MBR partition:
1. First find the Windows installation drive. To do this, on the Command Prompt window, enter the following command into:
dir C:
Note:
If the Windows folder is displayed, follow the steps below. If the Windows folder is not displayed, enter the commands by replacing C: with the names of other drive letters (such as dir d :, dir e :, .) until the mail folder is found. Windows entry.
2. After finding the drive with the Windows folder, enter the following command to create the boot files (boot files) on the drive and press Enter:
bcdboot D: Windows / SD:
Note:
If Windows is stored on another drive, replace D with the Windows drive letter.
3. After the Boot file is created, open the DISKPART prognosis again by entering the following command into the Command Promt window:
diskpart
4. At DISPART, enter:
list disk
5. Enter the command below into the Command Prompt window and press Enter:
select disk X
Note:
In the statement above X is the number of drives containing the operating system, such as drive 0.
6. Enter each statement below into the Command Prompt window and press Enter:
1. list volume
2. select volume X (where X is the Volume number containing the Windows folder. In the example above the volume is 3).
3. active
![]()
7. Enter exit to close the DISPART tool.
8. Close all windows and restart your computer.
9. Now you can remove Windows 10 Boot Media and restart your computer normally.
Part 2: Fix boot file errors (boot files) on GPT partitions
1. First find the Windows installation drive. To do this, on the Command Prompt window, enter the command below and press Enter:
dir C:
Note:
If the Windows folder is displayed, follow the steps below. If the Windows folder is not displayed, enter the commands by replacing C: with the names of other drive letters (such as dir d :, dir e :, .) until the mail folder is found. Windows entry.
2. Next open the DISKPART utility by entering the command below into the Command Prompt window and then press Enter:
diskpart
3. At the DISKPART command, you enter:
list disk
4. Next enter the following command and press Enter:
select disk X
Note : in sentence l, above command, X is the number of drives containing the operating system
5. Enter the command below and press Enter:
list partition
6. Find the partition named System .
7. Select the System partition by entering the command:
select phân vùng X
Note : where X is the partition number named System
8. Assign a drive to the System partition by entering the following command into the Command Prompt window and press Enter:
assign letter = S:
Note:
In the above statement, replace S with the drive letter name.
9. Enter exit into the Command Prompt window and press Enter to close the DISKPART tool.
10. Enter each statement below, after each statement press Enter:
1. cd / d S: EFIMicrosoftBoot
2. ren BCD BCD.bak
3. bcdboot C: Windows / l en-us / sm: / f UEFI
Note:
1. Replace S with the drive name you assigned to the System partition.
2. If Windows is on another drive, use that drive name to replace C.
3. In the third statement, the "/ l en-us" section used to set up the Windows language is English. If you want to set up another language, replace "/ l en-us" with the appropriate language code.
11. Close all windows and restart your computer.
12. You can now remove Windows 10 Boot Media and restart your computer normally.
Refer to some of the following articles:
- 4 ways to fix USB errors without formatting: 'Windows was unable to complete the format'
- Summary of some ways to fix Windows 10 crash, BSOD error and restart error
- Unusually high CPU error correction due to TiWorker.exe on Windows 10 / 8.1 / 8
Good luck!
You should read it
- How to fix VCRUNTIME140_1.dll not found, is missing error in Windows
- Steps to fix error 0x8004FC12 on Windows 11
- How to fix 'This App Can't Run on Your PC' error on Windows 10
- 6 ways to fix Bluetooth errors not in Device Manager on Windows 10, 8.1, 8, 7, XP, Vista
- How to fix Windows Sandbox error 'No Hypervisor Was Found 0XC0351000'
- How to fix VPN error 619
- Instructions to fix Windows error does not boot
- How to fix Msstdfmt.dll Not Found error
May be interested
- What is the directory $ WINDOWS. ~ BT, can delete $ WINDOWS. ~ BT or not?folders such as $ windows. ~ bt and $ windows. ~ ws are directories related to the windows 10 upgrade process. these folders may appear on windows 7, 8 and 10 and more. , these folders are hidden folders, so to see these directories you have to perform some additional operations to display the directory.
- Fixing the error 'WiFi doesn't have a Windows 10 configuration IP validation'however, in some cases if the ip address of the system (internet protocol) is misconfigured, it will cause a 'wifi doesn't have a ip configuration validate' or 'ethernet doesn't have a configuration ip validation' or 'wireless network không có một cấu hình ip hợp lệ'.
- Why is it disabled but Cortana still runs in the background?although disabling cortana virtual assistant and on windows 10 computers users use local search to find everything. however, when opening task manager, some users find that cortana still runs in the background. so why is that? the answer will be in the following article of network administration.
- How to disable Lock Screen lock screen on Windows 10 Anniversary Updatewindows 10 anniversary update updates include a group policy update available on enterprise and education versions. therefore users can use group policy to disable lock screen lock screen on windows 10 anniversary update.
- How to disable Lock Screen lock screen on Windows 8, 10on windows 8 and windows 10, lock screen lock screen allows users to select any image as wallpaper as well as display the date and time on the screen when logging out of windows. however, when logging back into windows, users are forced to use the mouse to bypass this lock screen lock screen.
- Instructions for displaying battery percentage on Taskbar bar Windows 10by default, windows 10 displays the battery icon on the taskbar system tray so users can see how much the battery is charging on their windows 10 computer. however, if you just look at it, users will be very difficult to imagine the actual battery capacity to be charged anymore.