FIX: An operating system wasn't found on Windows 10 or Windows 8.1 (Solved)

The following error may appeared on Windows 10 or 8.1 computer during boot process "An operating system wasn’t found. Try disconnecting any drives that don’t contain an operating system. Press Ctrl+Alt+Del to restart". 

The "An operating system wasn’t found" error can be displayed on Windows 10 or Windows 8.1 computers, after a Windows upgrade (e.g. from Windows 8.1 to Windows 10), a BIOS update, or after you have cloned your hard drive to another disk.

operating system wasn't found

In this tutorial you can find detailed instructions on how to resolve the ""An operating system wasn’t found. Try disconnecting any drives that don’t contain an operating system. Press Ctrl+Alt+Del to restart" on Windows 10 or Windows 8 or 8.1 OS.

 

How to fix: "An operating system wasn’t found" error on Windows 10 & Windows 8.1

In order to fix the "An operating system wasn’t found" problem on Windows 10 you need a Windows 10 (or 8, 8.1) Boot USB or DVD Media (Installation Media). – If you don't own a Windows 10 Boot Media, then (from another computer) you can create one, by following the instructions mentioned on these articles:

Important: Before you  continue to troubleshoot the problem by following the steps below, try to boot into Windows after you have:

A. Set your internal hard drive (with the installed OS) as the first boot device on the BIOS Setup settings (or the Windows Boot Manager if you own an UEFI System).
B. Disconnected any other USB drives (or devices) connected on your computer.

 

Method 1: Perform a Windows Startup Repair.
Method 2. Configure and Repair the Boot files.

 

Method 1: Perform a Windows Startup Repair

1. Place the Windows Boot Media on the computer and boot from it.

2. At the first setup screen, choose your Language, Time – Currency and your keyboard input method and click Next.

Windows 10 startup repair

 

3. At the next screen select Repair your computer.

Repair your computer

 

4. Then click Troubleshoot –> Advanced options –> Startup Repair.

Startup Repair

 

5. Wait while Windows diagnosing and fix problems.

6. When the Startup Repair is completed try to boot in Windows normally.

– If your still receive the "operating system wasn’t found" error or if the Startup Repair couldn't repair your PC, continue at Method 2 below.

 

Method 2. Configure and Repair the Boot Files (Options).

1. Place the Windows Boot Media on the computer and boot from it.

2. At the first setup screen, choose your Language, Time – Currency and your keyboard input method and click Next.

Windows 10 setup

 

3. At the next screen simultaneously press the SHIFT + F10 keys to open the command prompt.

windows setup

 

4. At the command prompt window, type the following command to open DISKPART utility and press Enter:

  • diskpart

diskpart

 

5. Then give the following command to find out if your disk is set to GPT or MBR partition table and press Enter:

  • list disk

Look at the GPT column to see if it has an asterisk (*).

– If you see an asterisk (*), that means that your disk's Partition Table is GPT.

– If you don't see an asterisk, that means that your disk's Partition Table is MBR.

(In this screenshot the partition table is MBR)

list disk mbr

(In this screenshot the partition table is GPT)

list disk gpt

 

6. Type exit and press Enter.

7. If the partition table is MBR then read and apply Part's 1 instructions to resolve the "Operating system wasn’t found" problem, otherwise – if the partition table is GPT – read and apply Part's 2 instructions.

 

PART 1. Fix Boot Files on MBR Partition Table

 

1. First, find out on which disk Windows were installed. To do that, in the command prompt window, give the following command: *

  • dir C:

* Note: If the Windows directory is displayed, then continue to the next step, otherwise continue by typing the next alphabet letter until you find which drive contains the Windows folder (e.g. dir d: , dir e:. dir f:, etc.).

(In this example the Windows folder is located at drive D🙂

dir c:

 

2. When you find out which drive contains the Windows folder, (in this example on the drive "D:"), give the following command to create the boot files on that drive and press Enter. *

* Note: If Windows are located on a different drive, change the letter D with that drive letter.

  • bcdboot D:\Windows /S D:

The System should return this message:
"Boot files successfully created "

boot files successfully created

 

3. After the Boot files creation, open DISKPART utility again by typing:

  • diskpart

4. In DISKPART prompt type:

  • list disk

list disk

5. Now type the following command and then press Enter:

  • select disk(Where “X “means the number of disk that contains the Operating System – e.g. “0”)

select disk 0

 

6. Then give the following commands in order (press Enter after typing each one of them)

  1. list volumelist volume
  2. select volume X (Where “X “means the number of Volume that contains the Windows folder. In this example is the Volume “3”)select volume 1
  3. activemake partition active

 

7. Type exit to close the DISKPART tool.

8. Close all Windows and reboot your computer.

9. Remove the Windows 10 Boot Media and boot to Windows normally.

You 're done! Let me know if this guide has helped you by leaving your comment about your experience. Please like and share this guide to help others.

 

PART 2: Fix Boot Files on GPT Partition Table

1. At first, find out on which disk Windows are installed: To do that, in the command prompt window give the following command: *

  • dir C:

* Note: If the Windows directory is displayed then continue to the next step. otherwise continue by typing the next alphabet letter until you found which drive contains the Windows folder (e.g. dir d: , dir e:. dir f:, etc.).

(In this example the Windows folder is located at drive C🙂

list directory command

2. Then open the DISKPART utility by typing the following command and press Enter:

  • diskpart

3. At DISKPART prompt type:

  • list disk

list disk command

 

4. Now type the following command and then press Enter:

  • select disk(Where “X “means the number of disk that contains the Operating System – e.g. “0”).

select disk command

5. Then type the following command and press Enter.

  • list partition

6. Find out which Partition is labeled as System.

(In this screenshot the Partition 4 is labeled as System)

list partition command

 

6. Select the System partition by typing:

  • select partition X  (Where “X “is the number of the partition labeled as System. e.g. “4”).

select partition command

 

7. Assign a drive letter (e.g. the letter "S") to the System partition by typing the following command and press Enter: *

  • assign letter=S:

* Note: If the drive letter "S" is already used, then give the next drive letter in alphabet.

assign letter command

 

8. Type exit and press Enter to close DISKPART tool.

9. Then give the following commands in order (press Enter after typing each one of them).

  1. cd /d S:\EFI\Microsoft\Boot\
  2. ren BCD BCD.bak
  3. bcdboot C:\Windows /l en-us /s m: /f UEFI

Notes:

1. Change the letter "S" if you have assigned a different drive letter to the System partition.

2. If Windows is located on a different drive then use that drive letter instead of "C".

3. The "/l en-us" part of the above command sets the Windows language to English. If you want to set a different language, then replace the "en-us" with the appropriate language code (e.g. "fr-FR" for France).

10. Close all Windows and reboot your computer.

11. Remove the Windows 10 Boot Media and boot to Windows normally.

You 're done! Let me know if this guide has helped you by leaving your comment about your experience. Please like and share this guide to help others.

If this article was useful for you, please consider supporting us by making a donation. Even $1 can a make a huge difference for us in our effort to continue to help others while keeping this site free: