MCT Created Media with 26200.8457 no longer boots after clearing and reinstall secure boot keys on ASUS Z390 motherboard

Why won't the May 2026 MCT media boot after clearing and reinstalling default secure boot keys on the Z390 motherboard? When I try to boot from this USB it goes back to the UEFI BIOS screen and won't boot. I had to switch Secure Boot mode to Other OS instead of Windows UEFI before I can clean install Windows. Also if I clear and reinstall the default Secure Boot keys from the BIOS I can no longer boot into Windows due to red Secure Boot Violation error unless I switch Secure Boot mode to Other OS and by doing this it also asks for the Bitlocker Recovery Key which is only stored in the Microsoft Account which is protected by two step verification which requires another device. The motherboard was made in 2018 and doesn't include the CA 2023 keys and ASUS still has not receive a BIOS update with the CA 2023 keys preinstalled.

Can you download the scripts from this thread?

Mount the USB drive, and run this script:

From your details, it sounds like MCT is picking the CA 2023 version of the boot files. There are two versions of the boot files, one using the legacy CA 2011 cert and another with CA 2023. Depending on your current list of Secure Boot certs, and the boot file's version, it will fail the Secure Boot security check.

And nothing works until you disable Secure Boot mode or pick "Other OS".

PS - It may be possible to update the certs for this ASUS Z390.

Keith Weisshar said:

The motherboard was made in 2018 and doesn't include the CA 2023 keys and ASUS still has not receive a BIOS update with the CA 2023 keys preinstalled.

Click to expand...

ASUS will not be providing new BIOS firmware for your Z390. I'm in the same boat with my Z370,
but I was able to update Secure Boot with the new certs.

MCT created USB media 26200.8457 has a bug.
Cannot open the menus when I hit "Repair my PC", it reboots the main OS instead.
Fails the same way with Secure boot disabled.