Windows 10: Lost UEFI when reinstalling Windows 10

I have a laptop that had Windows 7, but was upgraded to Windows 10 with the free upgrade option.

Everything was getting really slow and full of unneeded software, so I decided to do a clean reinstall Windows 10. I downloaded a copy of Windows 10 to a USB drive as directed here: Download Windows 10

But I couldn't boot from the USB drive unless I turned off UEFI and the "secure mode" settings, and instead used the legacy BIOS boot settings without "secure mode".

I then deleted all partitions and reinstalled Windows 10 on the new blank memory.

Eveyrthing went fine, but when I try to change the settings back from legacy BIOS to UEFI it says there is nothing to boot. It only works when in legacy BIOS mode.

I want my installation to be very secure from hacking, so how can I reinstall the UEFI settings so I can turn the secure mode back on?

I have no idea how all this stuff works - but from Googling I think I messed up by deleteing the partition that held the UEFI setting. Any way I can reconfigure that and fix what I did?

:)

 

Windows 10 clean install will not activate

My main desktop shipped with Windows 7 shortly before Windows 8 was released. It is fully UEFI and Secure Boot capable, but enabling that prevents reinstall of Windows 7, which requires an MBR-initialized disk (UEFI requires a GPT-initialized disk). I
upgraded to Windows 8 when it came out and installed a GPT-initialized SSD for my boot disk at the same time. I did not realize that my ability to boot Windows 7 was lost in the process, but I learned that I just can't boot Windows 7 on this device without
re-initializing the SSD to MBR.

If your computer only has Legacy BIOS mode, it makes things simpler, but it seems that when Windows 10 detects a UEFI-capable device it defaults to trying to set the computer up with a GPT partitioning scheme. That requires removing all drive partitions
to convert the drive to GPT and prevents Windows 7 reinstallation without first undoing all of that and disabling UEFI to convert the disk to MBR. To go back to Windows 7 then requires a clean install after making BIOS and disk changes.

Not sure if this is your situation too, but it sounds like a possibility.

So if your goal is Windows 10 on a UEFI computer that currently does not have Windows 7 installed, you would have to:

• disable UEFI (or enable compatibility mode to allow Windows 7 install)
• convert the disk to MBR
• reinstall and activate Windows 7
• upgrade to Windows 10, which should auto-activate
• then enable full UEFI and Secure Boot
• wipe the disk of all partitions, so that it can be initialized as GPT
• clean install Windows 10 (which should auto-activate)

 

Windows 10 UEFI BIOS

It looks like your hardware supports both the new firmware standard (UEFI), and the old firmware standard (Legacy or BIOS).

Based on your description, it seems that Windows 10 was installed in UEFI mode. Legacy firmware can't see UEFI, and that's why when you enter Legacy, you can't see the newer, UEFI-based Windows 10.

The solution? Reinstall Windows 10 using legacy boot instead of UEFI.

 

Your installation media apparently was not UEFI bootable.

Follow these instructions to create a bootable Windows 10 USB drive for Legacy BIOS and/or UEFI:
Create Bootable USB Flash Drive to Install Windows 10

2. Set your BIOS to UEFI defaults then disable Secure Boot and Fast Boot (if enabled):
(You can turn those 2 options back on after the installation is completed)

3. Select the UEFI option when booting from the new media and away you go!

Good luck,

 

I do believe you made the error of selecting the first one (BIOS or UEFI). It won't boot in UEFI, <<no boot device was found>> will be shown. You will get the same result with Ubuntu or Opensuse. Second and third option works.

 

Got it working thanks guys!

I used the same boot USB I had before, but this time I selected UEFI for installation in the boot menu. I must have misse that somehow the first time around.

 

That's great news! Glad you got it sorted and thanks for reporting you fix too!

Please mark this thread as solved.

regards,