2nd stage of Windows 11 install and subsequent boots fail with "Operating System not found" - Need to disable "Secure Boot" in BIOS

Hello,

When I upgraded to Windows 11 on a laptop the second stage of the Windows 11 install fails at reboot with the error "Operating System not found".

I used Flyoobe v1.23 (Stable) to perform the upgrade to Windows 11 (version 25H2) from Windows 10.

For the installation to continue, I needed to disable Secure Boot in the BIOS.

Once installed I still need to have Secure Boot disabled for the computer to boot into Windows 11.

The hard drive is GPT and EFI so Secure Boot should work.

The BIOS was always set to UEFI and Secure Boot so nothing has changed since Windows 10 was running on it.

Is it normal for the computer to fail booting if Secure Boot is enabled when FlyOOBE has been used to upgrade a Windows 10 computer to Windows 11?

Am I forced to leave Secure Boot disabled for Windows 11 to boot?

Regards,

fbagnato