An operating system was not found......

Page 1 of 2 12 LastLast

  1. Posts : 5
    Windows 10

    An operating system was not found......

    I did the conversion from Windows 7 to Windows 10 about 1.5 months ago.
    This is a Dell Vostro w/Intel Corei5 desktop

    All was fine until I attempted to wake the computer from sleep mode recently and got the following error.

    An operating system was not found. Try disconnecting any drives that don't contain an operating system
    Press Ctrl+Atl+Del to restart

    I disconnected the two external drives I had connected and tried again with the same result.

    On startup, I've hit F12 to run through the Dell ePSA Pre-boot system assessment and it passes all the tests
    System, Cables, OS boot Path, Hard drive, cd rom drive, video card, cpu fan, system fan processor and memory.

    I have the original 7, 64 bit installation disks, but nothing for Windows 10. What's the best way to get this thing going again?
    I appreciate any help you all can give me.....
      My Computer

  2. Posts : 7,086
    Windows 10 Pro 64 bit

    This may indicate your Windows boot configuration has become corrupted or you have a disk error.

    I suggest you boot from your Windows 10 installation CD / USB drive and try the startup repair option. See You will need to create a Windows 10 installation disk if you don't have one using the Windows Media Creation Tool. See You can create a bootable Windows 10 USB drive or ISO file you can burn to create a bootable CD.

    Come back for more help if needed.
      My Computers

  3. Posts : 3,365
    W10 Pro x64/W7 Ultimate x64 dual boot main - W10 Pro Insider Preview/W7 Pro x64 - remote pc

    Hello Coanbru Welcome to the Ten Forums!

    Part of Steve C is correct. You can download and use the Media Creation tool to download and save the "Windows.iso" file as the 10 download is labeled by default you can easily save as "Windows 10 Home or Pro x86(32bit) or x64(64bit).iso" to easily ID the particulars. The initial option won't help being the instant online upgrade you skip as well as creating the usb flash drive unless you have at least an 8gb or 16gb flash drive available. If not skip the option to burn to dvd since the download for the present Threshold 2 Update being the 10586 version 1511 build contains both the 32bit and 64bit flavors for both 10 Home and Pro editions resulting in a larger 5.48gb size iso file on disk! Too big for any blank dvd-r and you would need at least a 6gb flash drive hard to find if not an 8gb or 16gb to see written to immediately or wait in order to save the iso to a folder to have onhand! That can help.

    If the Dell model lacks a boot device menu which is doubtful like some laptops only boot from optical not seeing the F key assigned to select the drive you would need to borrow someone else's 10240 media or other Windows Insider build dvd if that model should only boot from optical. Most likely however once you have a the 10 media made up you will be booting from a flash drive and be able to use the Recovery tools while the hard drive is still suspect at the moment until confirmed by other means the drive is still working and the data cable is still good and plugged in fully not being loose at all.

    Since 10 was activated if push comes to shove you can now perform a full clean install if necessary to get 10 running again and eliminate the worry about potential problems that are typically seen at some point with upgrade installs. You may have run into one there while 10 would tend to get buggy not simply disappear on you suggesting a possible hardware issue.
      My Computer

  4. Posts : 7,086
    Windows 10 Pro 64 bit

    I forgot to mention the obvious check that you are booting from the correct drive. Enter your BIOS on start up and confirm in the boot priority screen that your PC is set to boot from the disk where Windows is installed.
      My Computers

  5. Posts : 3,365
    W10 Pro x64/W7 Ultimate x64 dual boot main - W10 Pro Insider Preview/W7 Pro x64 - remote pc

    With only one internal OS drive that would be seen as Disk 0 in the Advanced section of the bios setup and should be at the top of the list if you have a second drive present where that will set it as the first drive the bios looks at for the OS at post time. Those quick tests are not always 100% accurate I should add here with the cables checking out all good being a possible item of concern for why you are seeing the missing OS indication.

    The power connections are what those tests would be about as far as any of the drives optical or hard drives while a bad or loose data cable wouldn't show as bad since the tests are looking at voltages. The bios can still run tests on the drive through a loose or flawed cable while the rest of the same is no good as far as the data and not simply the voltage signals sent from the onboard controllers. You can't rule those while they are less likely to be problems for the most part in comparison to the old flat ribbon type Iide drives used in years past that would stiffen up and loose contact.

    Trying a 7pin replacement cable on the drive would be a thought before assuming the drive either failed or the upgrade to 10 is no good despite the fact upgrades can turn out buggy. If the partition table isn't trashed missing OS errors often will point to a hardware like drive if not cable problem.
      My Computer

  6. Posts : 5
    Windows 10
    Thread Starter

    Thanks guys for the info. I hope to be home tonight to try to decipher all this info.
    A couple of quick points.
    - Since Win 10 was pushed to me with the free upgrade, I don't have any disks
    - I do have a 32gb thumb drive I can use.
    - I do have the ability (hitting F2 or F12 on power up) to control where the computer boots from.
    - Even though the computer passed the Dell tests I mentioned above, I'll take the cover off tonight, blow out the dust bunnies, and re-seat cables. The disk passed the Dell test as mentioned above.
      My Computer

  7. Posts : 58

    My son brought back a computer that I had given him with windows 10 on saying it wouldn't boot up, there was a second hard drive in which I disconnected, the machine booted up fine. I reconnected the second drive, it refused to boot up again, I shut it down, replaced the cable to the second hard drive, rebooted, it worked fine and both drives were fine.

    Just goes to show, it was the cable to the second hard drive causing the problem.
      My Computer

  8. Posts : 3,365
    W10 Pro x64/W7 Ultimate x64 dual boot main - W10 Pro Insider Preview/W7 Pro x64 - remote pc

    That was from seeing 10 installed upgrade or other with the 10 installer getting confused on where to put the boot files and temp install folders! Having two storage drives along with a second OS drive I first used to upgrade a clone of 7 on the upgrade wouldn't take! Later as I reviewed the Clean Install guide the notation about unplugging any non OS drives fit the bill! Once the two storage/backup drives as well as the previous 7 host/boot drive were unplugged the upgrade over the clone went immediately on! The upgrade came out buggy as all heck however but still went on!

    Now as for the mention of the cable even if the cable is good blasting the dust out and perhaps moving the OS drive's cable over to the next sata port on the board could see results?! If the first port has a problem with build up that would be something to try as well. Yet a loose contact in the cable could be another source.

    With this type of problem especially now with 10 as far as being sensitive to non OS drives for example while previous versions simply put everything on what was seen as Disk 0 the first drive regardless if others were present or not 10 loses brain functioning when other drives are present! And yet MS expects everyone to rush to upgrade without any provisions considered about any of this first??? Now the 10 as an update no longer sees the reject option as of late!
      My Computer

  9. Posts : 5
    Windows 10
    Thread Starter

    Well I only had time enough tonight to blow out the dust and re-seat cables...
    No luck

    I then went to:
    Windows 10 ISO Download - Windows 10 Forums
    to use Option 2, to Download Media creation Tool.

    Instead it walked me through downloading
    Win10_1511_English.iso (I saved this to a thumb drive)

    Where to next? Thanks
      My Computer

  10. Posts : 17,247
    Windows 11 Pro

    Coanbru said:
    Where to next? Thanks
    USB Flash Drive - Create to Install Windows 10 - Windows 10 Forums

    Option 2 is probably your best choice.
      My Computer


  Related Discussions
Our Sites
Site Links
About Us
Windows 10 Forums is an independent web site and has not been authorized, sponsored, or otherwise approved by Microsoft Corporation. "Windows 10" and related materials are trademarks of Microsoft Corp.

Designer Media Ltd
All times are GMT -5. The time now is 08:51.
Find Us

Windows 10 Forums