virtualbox.org

Hi!

I'm trying to re-run a few Ubuntu VM's from few years back, but I always just get this kind of an error:

Failed to open a session for the virtual machine MyVM.
VT-x is being used by another hypervisor (VERR_VMX_IN_VMX_ROOT_MODE).
VirtualBox can't operate in VMX root mode. Please close all other virtualization programs. (VERR_VMX_IN_VMX_ROOT_MODE).
Result Code: E_FAIL (0x80004005)
Component: ConsoleWrap
Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

What might cause this issue?

My host is Win 10 + Virtual Box 5.2.2.

AlliumPorrum wrote:VT-x is being used by another hypervisor (VERR_VMX_IN_VMX_ROOT_MODE).

AlliumPorrum wrote:My host is Win 10

After making 110% sure that Hyper-V is disabled in the Windows Features, you might want to make sure that Fast Boot is disabled and do a cold boot (i.e. shut down the host for a minute or two).

You also must make sure that nothing else is using Hyper-V, things like antivirus, debuggers, emulators, etc. Check out the article Diagnosing VirtualBox Hardening Issues to get some ideas...

socratis wrote: After making 110% sure that Hyper-V is disabled in the Windows Features....

Ok, thanks Socratis, I did not know this... How exactly can I make sure that it is disabled?

Go to Control Panel (the real one, not the "Windows Settings" crap in W10), then "Programs and Features", then "Turn Windows features on or off." If Hyper-V is checked in there, it's enabled.

You can also just go right click on the start button, run, "OptionalFeatures.exe". The "Hyper-V" box should be clear - not checked or shaded.

Ok, I checked the Hyper-V, and it was already disabled. Then, as instructed, I disabled the fast boot- option (which was ON), and that did it! Thank you very much for your help!

Great, thanks for the feedback. Marking as [Solved].

I checked all the diagnostics and. Hyper v disabled, fast boot is off and error not resolved. Can you please say what am i missing

Related FAQ: I have a 64bit host, but can't install 64bit guests.