Comment 25 for bug 1668148

I just fall myself in this case and I think this example and my reflection can help this discussion ...
(Why do I think that you need not only a message, but also a choice box (legacy / efi) when installing ...)

My bios has efi disabled. I configured my boot start without efi with:
1 - cd / dvd
2 - usb
3 - HDD
and I just realized that as soon as I touch this config, it automatically duplicates my choices for devices in:
4 - cd / dvd efi
5 - usb efi
when I start with a cd or a usb key, it goes into auto boot and start directly by switching to 4 or 5 (!). Basically it forces the boot efi even if it is disabled and even if you have filled something else manually ...
that's how I got an "install failed"

If I start by doing F(4-5-6-7...) for boot option: no pb: I have my order manually filled (+ the duplicate choices in efi)

I have an ASUS with a bios update (but seeing what I read on the forums, it must not be the only ones to force the efi this way ...)