Sometimes while trying to boot Windows, you receive Boot Error: An operating system wasn’t found. Try disconnecting any drives that don’t contain an operating system. Press Ctrl+Alt+Del to restart. Especially after Windows 10 upgrade, BIOS update, Cloned your hard drive to another disk, or perform a system restore you may encounter this error. Well, the most probable culprit behind this problem is the missing BOOTMGR file at the root directory of System Reserved Partition. Again corruption of system files is also causes critical to the proper functioning of Windows.
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An operating system wasn’t found windows 10
If you are also struggling with a similar problem, here we have different solutions apply to fix an operating system that wasn’t found Error permanently.
Start with basic disconnect All connected external devices such as a printer, scanner, external HDD, etc, and restart PC check if windows boot normally.
- If you are a Laptop user simply remove the battery,
- Press and hold the power button for 30sec.
- Now only Connect the power supply and power on the laptop,
- Check if windows start normally.
Set Hard Disk As the first boot device
- Access BIOS setup utility screen using del, F2, F12, or Esc while boot process,
- Move to Boot options using the arrow key,
- Here change the 1st boot device as your internal HDD.
- Press F10 to save this will Restart windows
- Now check if Windows boots normally.
Perform Windows Startup Repair
Perform windows startup repair, help with diagnosing and fixing the problems prevent windows start normally. As windows won’t start normally, we need boot from an installation media, If you Don’t read How To Create Windows 10 Installation media. windows
- Let’s start PC from Windows i0 Installation media,
- Skip the first screen and click Next.
- Now on the next screen select Repair your computer.
This will restart windows now next click Troubleshoot –> Advanced options –> Startup Repair.
Wait while Windows diagnosing and fix problems. When the Startup Repair is completed this will automatically Restart windows and try to boot in Windows normally.
Repair Corrupted Boot Files
Still having problems, startup repair unable to fix the same? don’t worry let’s repair the boot file that probably helps fix most of Windows 10 boot problems.
- Again boot from installation media and access advanced options,
- This time click on the command prompt,
- Here At the command prompt window, type command diskpart and hit enter key to open DISKPART utility.
- Now type list disk and hit enter key to find out if your disk is set to GPT or MBR partition.
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.
Now Fallow bellow We have two Different solutions for different partitions. (MBR Partition table and GPT Partition Table)
Fix Boot Files on MBR Partition Table
Note: if you have a GPT partition skip this and Fallow next step
Find out the Drive letter where windows are installed. You can do this by type command type list volume and hit the enter key. you will notice the Drive letter where windows are installed as Boot.
Now When you find out which drive contains the Windows folder, (For me it’s drive “C:”), give the following command to create the boot files on that drive and press Enter.
bcdboot C:\Windows /S C:
* Note: If Windows is located on a different drive, change the letter C with that drive letter.
After executing the command Again open DISKPART utility by type command diskpart and hit enter key. Here on-disk part utility type list disk press enter key.
Select the disk letter by using the command select disk 0
Type Fallowing commands one by one as per instructed bellow
- list volume
- select volume 3 (Here select the volume number which contains the Windows operating system)
Type exit to close the DISKPART tool, that’s all now remove the installation media and reboot your computer.
Fix Boot Files on GPT Partition Table
If you have the GPT partition Table follow below.
Type diskpart and hit enter to open the diskpart utility and type bellow command.
select disk 0 ( Select the disk number ).
Next type command list partition and hit enter key.
Here Find out which Partition is labeled as System, and Select the System partition by type bellow command
select partition X (Where “X “is the number of the partition labeled as System. e.g. “4”).
Assign a drive letter (e.g. the letter “H”) to the System partition by typing the following command and press Enter: *
* Note: If the drive letter “H” is already used, then give the next drive letter in the alphabet.
type exit and press Enter to close DISKPART tool.
Again Type Bellow commands one by one
- cd /d H:\EFI\Microsoft\Boot\
- ren BCD BCD.bak
- bcdboot C:\Windows /l en-us /s m: /f UEFI
Note: Change the letter “H” if you have assigned a different drive letter to the System partition.
That’s all Remove installation media and Now Close all Windows, reboot your computer. Check the problem is solved.
If all the above methods failed then the check by performing windows clean installation.