Windows 10: An operating system was not found......

Discus and support An operating system was not found...... in Windows 10 Support to solve the problem; 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... Discussion in 'Windows 10 Support' started by Coanbru, Jan 3, 2016.

  1. Coanbru Win User

    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.....

    Coanbru, Jan 3, 2016
  2. Ugo Lopez Win User

    an operating system was not found

    You should. If you want to be 100% sure, please share a picture as above and I'll immediately let you know
    Ugo Lopez, Jan 3, 2016
  3. an operating system was not found

    sir i created 3 partition

    2 with ntfs and 1 with ext4
    kcltangdhar, Jan 3, 2016
  4. Steve C Win User

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

    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 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.
    Steve C, Jan 3, 2016
  5. 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.
    Night Hawk, Jan 3, 2016
  6. Steve C Win User
    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.
    Steve C, Jan 4, 2016
  7. 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.
    Night Hawk, Jan 4, 2016
  8. Coanbru Win User

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

    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.
    Coanbru, Jan 4, 2016
  9. Tacit Win User
    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.
    Tacit, Jan 4, 2016
  10. 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!
    Night Hawk, Jan 4, 2016
  11. Coanbru Win User
    Well I only had time enough tonight to blow out the dust and re-seat cables...
    No luck *Sad

    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
    Coanbru, Jan 6, 2016
  12. NavyLCDR New Member
    NavyLCDR, Jan 6, 2016
  13. An operating system was not found......

    What I did originally was download each 10 iso separately for both Home and Pro as well as in the 32bit and 64bit flavors as well as the dual 32/64 iso for each edition back then. Since the Threshold 2 came out however you are now looking a larger download of 5.48gb on disk compared to the 2.8gb for 32bit and about 3.2gb for the 64bit flavor. An 8gb or 16gb flash drive will of course be needed since you likely won't find much of anything between the 4gb and 8gb sizes to start with except for custom made used for promotional purposes by different companies.

    Option Two in the guide there will be the Rufus tool. Here I had originally downloaded the trial for the UltraISO program 6yrs. back when 7 was just getting underway while MS had provided another tool back then. Since Windows isn't running you would need to see the 10 media made up over having mounted the "Windows.iso" as it will download as unless provided a new name like "Windows 10 TH2 Combination.iso" which it is since both Home and Pro, 32bit and 64bit options are now all rolled up together.

    Once you boot live from the media making sure only the destination OS drive is plugged in you will then have the options for Upgrade or Custom where you can decided whether or not to upgrade over the 10240 or go for the fresh 10586 1511 TH2 install which most would prefer to see a clean install take place. The iso download will unfortunately be too big to burn on a blank dvd-r disk limited to about 3.8-4gb there.

    That can make it real awkward for any laptop that will only boot from optical if not the hd seeing the optical set as the first in the boot order and no way into the bios setup to change that. When assuming at first the drive went on a now 3yr. laptop upgraded from 7 to 10 during August that suddenly only sees a black screen while all the leds light up and flash as well as an upgrade for the size of the original OEM drive a new one went in.

    Unfortunately since it still sees a black screen without anything including any error displayed it might turn out to be the display adapter(most likely onboard graphics for that model) if not somehow bumped to the external monitor setting. Unfortunately lacking one with a standard vga adapter to test that idea as to why you only see a black screen with nothing on that. It might simply be the backlight for the display worn out? Laptops don't generally have any cables inside as a rule to worry about replacing.
    Night Hawk, Jan 6, 2016
  14. Coanbru Win User
    From the Microsoft Tech Bench,
    I did the Windows 10 ISO Download with the following choices, in BOLD below

    Windows 10
    Windows 10 KN
    Windows 10 N
    Windows 10 Single Language


    32-Bit Download
    64B-Bit Download (since my original Win 7 installation DVD was 64 bit)

    This downloaded a file Win10_1511_English_X64.iso from the Microsoft tech bench. (3.9gb)
    I copied this file to my 32gb thumb drive

    I downloaded rufus.exe to the desktop of a working computer

    I ran rufus and created a bootable USB disk.

    MBR partition scheme for BIOS or UEFI
    4096 bytes
    x quick format
    x Create bootable disk using -> ISO image
    x Create extended label

    Click Start

    It created a startup file on the thumb drive
    placed thumb drive in the non-working computer, tried to boot, and it didn't find it.

    Started over again with the above thinking I did something wrong, and now when I try to create the bootable USB using Rufus, I get
    Error: Access to the drive is denied.

    I formated the USB to NTFS (it was Fat32 before) and retried everything above.... with the same
    Error: Access to the drive is denied.

    Help! Any ideas? am I doing or not doing something stupid? (Be nice now)

    Thanks big time in advance.....

    I put this USB in the non working computer and attempted to boot from the USB

    I verified it was pointed at the USB as the first boot drive.... no luck.

    1) Would it help, or should I try to used the original Windows 7 professional 64 bit installation disk.

    2) Was there an option in creating the windows 10 *.iso disk, to choose between Home or professional versions?
    3) Was the version of windows 10 that got pushed to us Home or professional?

    I ran Rufus, using step 7 (Create bootable USB Flash Drive for installing Winwows 10 using legacy BIOS (without UEFI)
    Coanbru, Jan 7, 2016
  15. Coanbru Win User
    Here a screenshot of the rufus input, and the logfile

    An operating system was not found...... [​IMG]
    Coanbru, Jan 7, 2016

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

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