Can only install an OS with Secure Boot disabled

Question

I made the dubious decision to install Windows 11 on my perfectly running Lat 7400 2-in-1 with Windows 10 Pro installed. I destroyed the disk completely using Hirens Boot CD first, then used a Rufus burned 25H2 image of Win11 Pro to install on the laptop - all good; then i made the mistake of uninstalled Edge with win11 tweak tools, which made Onedrive refuse to run full stop. after 3 hours of fighting, i decided to rebuild; Using the same USB installer i had originally. windows installed, then rebooted and....nothing. power cycled and it then went into a boot loop of pre-boot assessment screen, before reporting that there were no bootable drives available. booting from the usb drive also refused and caused the same response; booting into the uefi screen i saw the error "bootmgr has a security validation or internal error"

I then tried to boot from the Hirens USB - same problem; then i tried a USB device imaged using the MS media tool - same outcome each time. i even pulled the battery and CMOS, reset everything to defaults, still the same problem. I then pulled the drive, scanned it on my desktop and then destroyed the partitions; reinstalled in the laptop and....no change. In the end i DISABLED secure boot in the BIOS - and Windows 11 (Rufus) installed and rebooted fine. after updates installed, i turned secure boot back on and everything remained fine. then i decided to install a completely virgin win11 image from the ms tool - installer ran no problems, deleted all drive partitions, and got to the reboot stage after installing.....and back to the pre-boot check screen and no OS available.

Tearing my hair out now - machine has the latest 1.39 BIOS installed this week (not sure if it was before or after the first reinstall...) and i'm out of ideas. even tried creating images on 3 different machines, with the same problem again.

Has anyone else had this issue? Win11 is meant to do a hard NO is Secure Boot is disabled, but for me it's the only way i can get any OS on it.

One thing worth noting; if there is an OS on the machine and secure boot is enabled, then it will boot from the same USB drives it later refuses?

Tesla1856 · Answer

Don't use Hiren or Rufus.

Verify computer passes ePSA-Diagnostics (outside of Windows).
NVMe-SSD should be "DiskPart cleaned" back to un-initialized/raw.
BIOS set to UEFI-Mode and AHCI
- Some users report that SecureBoot needs to be OFF during actual Windows install, but I always leave it ON.
Only that one SSD installed/connected for now
F12 on boot to boot USB-FlashDrive from microsoft.com Media Creation Tool
https://www.microsoft.com/en-us/software-download/windows11
Install Windows to un-allocated/un-partitioned space
- It will initialize the NVMe-SSD as GPT, and format as NTFS
Refrain from installing any drivers from support.dell.com (ie, no "heavy" Dell Utilities or Intel driver-suites)
- Maybe Intel-Chipset (if your computer is very new) otherwise ...
- - Try to get all drivers from Windows-Update and nvidia.com
- I don't use SupportAssist

You do this to see if "the hardware" is good after-all.

After your Device-Manager is clean, you should be able to re-enable SecureBoot if you disabled it earlier during initial install.

Notes:
1. If semi-forcing Windows-11 onto an older (non- UEFI) Legacy BIOS computer, the Windows installer might decide to Initialize the main drive as MBR instead.
2. While sometimes not obvious, it IS still possible to install Windows with only a Local (Admin) Account.

Latitude

Can only install an OS with Secure Boot disabled

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