Selected file is not a proper bios!

[CattoBusiness]

I keep getting the error "Selected file is not a proper bios!" when I try to flash the patched file onto the bios and even when I use old original files (2016 for example) I keep getting the same error... I'm using a Z170-P and I have a Intel Arc A380 and I want to flash it so I can get resizable bar support.

[MrAnonymous7122]

I also have the same problem with an Asus H110M-R. I was following the instructions to enable ReBAR but the current BIOS would refuse to flash it. Also note that these somewhat newer Asus motherboards take .cap files for BIOS (The Z170-P is also Asus and requires a .cap file for BIOS). Mine wouldn't let me flash a .rom and I got the error above when saving the BIOS as bios.cap as its name. Windows showed it as a .cap file but I think that's just purely file extensions. Is it possible for UEFITool to save modified BIOS files as .cap or is it just saving a .rom file that the system believes it to be a .cap? The latter would make sense for this issue however is it possible to add this to UEFITool? I'm no expert but someone on superuser told me that there's a way to add .cap header to .rom file to make it a .cap file? This may be completely wrong and apologies if it is something that would be time consuming to add. Not sure if this is relevant but the version of UEFITool that the guide recommends is this.