Since I don't use Windows and can't test any of this I don't know if this will help or not.Jonathan Mansbridge wrote:I am trying to install debian on a Z8 windows 10 machine. ... What do I try next?
I have seen posts that say that secure boot and fast startup(which is a type of hibernation) must be turned off in order to dual boot. I think those things are supposed to be done before trying to install a dual boot.
There is this page from the Debian Wiki that might be applicable.
https://wiki.debian.org/GrubEFIReinstall
But as I stated at the outset, I have not and cannot test it so you should probably wait until someone who can answer with authority comes along and shares their experience of actually having done it.
Actually, you might get more attention if you started a new thread of your own, being down at the bottom of this one your question might not be noticed as well.
By the way, if that is the HP Z8 that you are refering to, it looks like a classy system, certainly more than I could afford.