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RaviKaurav
Copper

"An operating system was not found" error while trying to reinstall windows

Hi everyone,

I had windows 10 installed on my Dell Inspiron 7720 laptop for around a year. I wanted to roll back to windows 8.1, so i downloaded the usb media from microsoft website.I booted from the pen drive and formatted all the drives. After that I proceeded to install windows 8.1. When the setup had just started copying files, my laptop shut down due to low battery. Now when i am trying to boot from usb or dvd, i am getting an error saying "An operating system was not found. Try disconnecting any drives that don't contain an operating system. Press Ctrl+Alt+Del to resart".

Also, when I am trying to change the boot order or to load default settings in bios, I am getting an error - "FORMSET 98FBBCFB-1392-4FDE-ABB8-C41CC5AD7D6D

Failed to save storage: Boot_mem-Boot_ITEMS. Status Access Denied"

Someone suggested me to reset the bios by reseating the CMOS Battery. Did that but still getting same error. I have run out of idea now, and desperately need help. If someone has any suggestion, please help me out.

Thanks,

Ravi Kaurav

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4 Replies
Philip_Yip
Indium

RE: "An operating system was not found" error while trying to reinstall windows

Is your bootable USB FAT32 formatted and using the GPT partition scheme for UEFI BIOS.

Is Secure Boot Enabled in your systems UEFI setup?

Have you tried with Windows 10 Installation Media?

Dr Philip Yip
Tech Enthusiast and Author of the Unofficial Dell Windows Reinstallation Guide

Windows FAQs and OEM Downloads


#IDoNotWorkFor Dell
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RaviKaurav
Copper

RE: "An operating system was not found" error while trying to reinstall windows

Yes, my USB is FAT32 formatted and using the GPT partition scheme for UEFI BIOS.

Secure boot is disabled and pc is set to boot in legacy mode because when it was set to UEFI, i was not able to get the windows installation started. It was after i disabled the secure boot and set to Legacy, and used some Diskpart command line options at windows installation screen, that I was able to get the installation started.

I did not try with windows10 installation media because I think my laptop will throw the same error message because i had tried using a rescue kit (Paragon rescue kit) but i got the same error message "An operating system was not found"

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Philip_Yip
Indium

RE: "An operating system was not found" error while trying to reinstall windows

Yes, my USB is FAT32 formatted and using the GPT partition scheme for UEFI BIOS.

That is setup for a UEFI BIOS... and will not show up with a Legacy Boot.

Dr Philip Yip
Tech Enthusiast and Author of the Unofficial Dell Windows Reinstallation Guide

Windows FAQs and OEM Downloads


#IDoNotWorkFor Dell
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ajaykbarve
Phosphor

RE: "An operating system was not found" error while trying to reinstall windows

I recently reinstalled windows 8 with help from Microsoft. Faced lots of issues but finally was able to find the solution myself. I assume you have created a USB bootable media and are installing from it. Do post exact steps you have followed and the picture of the error and I will try to hep. Mind you, I did not install Windows 10 but Windows 8 but there is not much different in terms of installation process.

Regards
Ajay
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