In loop unable to run VirtualBox on Win10 Pro x64

[dfatvb]

Hi,

I had latest 5.x running fine, but it was being slow. I recalled seeing various virtual and hypervisor setting in Windows add features and thought maybe it be faster with those on so I turned them on. While there I enabled Hyper-V, Windows Hypervisor Platform, and Virtual Machine Platform. Reboot, then 5.x wouldn't run saying VT-x not available. So looking up on Internet, saw some saying virtual box 6 (download latest) fixes this. So I installed that, but it didn't, so looking more it says you have to disable hyper-v, fine I did that, reboot but same error. So then I disabled the other two, rebooted, but now same error with a message to enable "Windows Hypervisor Platform". So I enabled it, but then still get VT-x not available. So then I disabled that, and enabled Virtual Machine Platform, still doesn't work and back to the message to enable "Windows Hypervisor Platform". Ugh.

How do I get VirtualBox to run?

TIA!!

[dfatvb]

Update - each failure then attempt to change features and then reboot would BSOD. I gave up on 6.x and went back to 5.2.x and everything is working again. I'll stay with 5.x until 6 becomes stable, if it becomes stable.

[socratis]

I recalled seeing various virtual and hypervisor setting in Windows add features and thought maybe it be faster with those on so I turned them on

No, no, no, on the contrary, you should disable them all!

The trick with VT-x is that it has to be shared, since it's "only one" available slot for its use. For example, VMware and VirtualBox do not use VT-x at the same time, but rather take turns. To put it simply, every program that uses VT-x should do this: VT-x lock, execute, VT-x unlock. This way other processes can use VT-x in turns.

On the other hand, Hyper-V permanently takes over VT-x and doesn't let anyone else use it. If a program uses VT-x from the moment it is loaded, and doesn't let go till the moment it dies, you have a problem. So, please complain to Microsoft about that.

Look at the topic "I have a 64bit host, but can't install 64bit guests" the 3rd post, for some Hyper-V enablers that we're aware of so far. Make sure that none of them is enabled.