message on boot: an operating system was not found

the_observer · Jun 12, 2023

Hi all,
i run in multiple problems with my pc's lately. Anyway you usually help me good and thank you for this.

The problem i have now is :
Short description:
When i start the pc i get the message : an operating system was not found

Detailed Description:
I had a faulty PSU and my ssd was not visible always to bios. At start i was not sure so i disk copied the ssd to another one and the problem was solved for a couple of boots. Afterwards it came up again so i thought the problem is the pSU.
So i replaced it and the ssd was visible again. Unfortunately something has happened with the partitions and i followed a tutorial to fix it and now i get the aforementioned message. Starting the pc from a usb I can see 4 partitions in the ssd. Do you have any suggestion , on how i fix this whole issue?

Thank you for your time reading this.

Regards.

James · Jun 12, 2023

If you go into your BIOS, is your OS SSD top of the list? I think something to try - and I know it sounds a bit strange, but has worked for me before.. Unplug EVERYTHING (but your monitor) from the PC. Then try booting it. Sometimes it tries to boot from those devices or something. There are lots of options to fix this, but if you want to see them all I found this page - How to Fix the 'Operating System Not Found' Error which should cover the solutions I was thinking about. Try numbers 4-9.

FreeBooter · Jun 12, 2023

In this video, i will show you how to fix "An operating system wasn’t found" error message in Windows 10 or Windows 11.

SIW2 · Jun 12, 2023

Most likely cause on mbr disk is that the system partition is not marked active.

I think I might still have an lga775 with e8400 and a couple of ram sticks plugged in. Don't remember binning it, might have put it away who knows where.

the_observer · Jun 13, 2023

Thank you for your answers.
Before i try any of the solutions let me show you what i see in the screenshots attached.
It is supposed that windows 11 and all programs it had are installed in partition c: based on the size.
As i am a noob i do not know what the E: and F: partitions are for.
At the moment from screenshot 03 seems that c: is flagged Boot. So shouldn't it boot ok?
Maybe i should delete partitions e: and f: ?

With this new info do you have a heads up to give me?

FreeBooter · Jun 13, 2023

Who's instructions are you following and what are you doing?

the_observer · Jun 13, 2023

I have done nothing yet from the suggestions above.
But before i post here i had run a tutorial i found on google trying to fix the problem but i cannot recall which it was.

FreeBooter · Jun 13, 2023

How about you follow my suggestions at my video, we go from there.

the_observer · Jun 13, 2023

I did as the video says and there is a change in deed.
The 4 windows appeared and the circle is loading.
The problem is that it does not leave this screen.
I will let it so for half an hour maybe it is updating or something.

Try3 · Jun 13, 2023

It is not normal to have drive letters assigned to the partitions your diagrams show as E:\ & F:\
Did you add the drive letters?

Denis

FreeBooter · Jun 13, 2023

In this video, i will guide you on how to Rebuild the Boot Configuration Data (BCD) to fix some Windows startup issues.

Please boot your computer with Windows Setup Media and from Windows Recovery Environment start the Command Prompt.

Please type below command into Command Prompt and press Enter key.

The following command will fix errors on the disk.

Code:

Chkdsk C: /f

Please replace partition letter C: with Windows installed partition letter. When the computer boots into Windows Recovery Environment (WinRE) environment, the drive letter assign to Windows partition may not be C: drive letter because Windows 7, 8 , 8.1 and 10 creates a separate system partition when it's installed from scratch. The system partition contains boot files WinRE assigns the system partition the C: drive letter and the Windows installed partition will be assigned any other drive letter, usually D: drive letter is assign to Windows installed partition. The Bcdedit | find "osdevice" command can be used to find out the drive letter of the Windows installed partition, the output of the Bcdedit command is similar to this osdevice partition=D:. The drive letter after partition= is the drive letter of the Windows partition.

Try3 · Jun 13, 2023

My Windows 10 installation USB did not contain BCDEdit, are you sure the Windows 11 one does?

All the best,
Denis

FreeBooter · Jun 13, 2023

Try3 said:
My Windows 10 installation USB did not contain BCDEdit, are you sure the Windows 11 one does?

All the best,
Denis

Strange it should do you should download new ISO image because my Windows 11 22H2 have this command.

the_observer · Jun 13, 2023

Try3 said:
It is not normal to have drive letters assigned to the partitions your diagrams show as E:\ & F:\
Did you add the drive letters?

Denis

No i didn't.

the_observer · Jun 13, 2023

@->FreeBooter
I will try it tomorrow because it is late here and let you know. Thank you for trying to help.
Also the videos are very handy.

FreeBooter · Jun 13, 2023

You are very welcome and i'm glad to know you like my videos!

Try3 · Jun 14, 2023

FreeBooter said:
Windows 11 22H2 have this command

Thanks.
I've just built & tested a new Win11 install USB and it does have BCDEdit.
Actually, I also think my memory about my Win10 install USB is faulty. I think it only lacked BCDEdit if I booted it as Legacy. ~~I'll re-test that when I get a minute.~~ Yes, my Windows 10 InstallUSB has BCDEdit when it is booted as Uefi.

All the best,
Denis

jimbo45 · Jun 14, 2023

two easy solutions :

1) boot Free macrium recovery and choose fix windows boot problems.

or 2) slightly more complex

a) boot the Windows install disk
b) choose repair system and then go into command mode
c) run diskpart
e) then list vol
On that there should be a hidden partition (efi) of say 100Mb (seems the default size)
f) select vol xx -- and assign letter=S
g) exit diskpart - I've assumed C is the main Windows disk and E is the the install image (from the cd or usb install device)
h) cd e:\sources
i) cd e:\
j) bcdboot c:\windows /s S: /f UEFI
k) exit and reboot system -- should work OK.

Cheers
jimbo

message on boot: an operating system was not found

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