This time I’m not showing some hot new stuff but rather just want to introduce you to an old friend of mine, the “multiboot could not setup the video subsystem” error of ESXi. Every now and then, when I re-install my home lab (this time ESXi 6.0U1), I run into this issue. And every time I loose hours of my life time trying to remember what I did the last time. This post is ment to safe you some time and help me remember what to do when I face it the next time.

It all started with ESXi 5, when UEFI boot was introduced. Now I don’t what to blame UEFI for being a crappy, overblown technology, which it is (altho there are open alternatives).

I just want point out that in most cases the issue is not that you’re using hardware that’s not on the HCL. Because that’s what you’ll find as a explanation when googling up the error message. What you’ll also find is, that the real issue supposedly is that the ESXi setup will try to output a screen with a resolution of 1024x768 pixels. If that’s not possible, e.g. because your monitor doesn’t support it, the setup will fail.

Now one could say “ha-ha, who has a monitor that doesn’t support 1024x768 these days?!”. Yes - right. But remember that that’s not the only reason why it might not be able to output that screen. In my case the combination of the integrated VGA on-board video and my monitor fails to boot as well, even if it (of course) supports 1024x768. I tried like three (3!) different monitors from different vendors: all fail.

So what did I do next? Thinking to know the issue (“your monitor is not compatible”) I tried to run a scripted install, without any monitor attached at all. That’s what the scripted install is for, right? Headless installs, right? Wrong. You can guess what happened: the setup wasn’t able to output the screen and BAM - there you go: “multiboot could not setup the video subsystem” jumped right in my face when I plugged in the monitor after a few minutes of inactivity.

Trying to remember what I did the last time I realized that the issue is not that hardware attached but that UEFI setup. After I lost another hour of my life time trying to fix other people’s crap, I just created a bootable copy using LiLi USB creator and used the non-UEFI boot. And of course it worked right away.

BTW: using Rufus USB creator for my bootable USB drive of ESXi 6.0, as some people do, produced a working UEFI boot (resulting in the multiboot error) but the non-UEFI based boot was not working. So if you’re facing the issue and you’re not able to use UEFI boot, then go for LiLi.

Hope this safes somebody a couple of hours.