After upgrading my host OS to Windows 10, I have noticed some problems with my guests so I looked around the settings and noticed that the number of CPUs and acceleration options are greyed out.. I didn't update the virtualbox nor did anything change with my guests since last time, so only I can think of is that the upgrade of host caused this.

Now I wonder if Win 10 introduced some fundamental changes that would somehow affect virtualization or is it only my problem?

VB version 5.0.1 Win10 as a host, Lubuntu as a testing guest (but all guests have the acceleration disabled in them)

Edit: BIOS virtualization settings enter image description here

  • Update VBox the version you are using does not fully support Windows 10 – Ramhound Sep 18 '15 at 10:43
  • What is the recommended version? 5.0.4 or 4.3.30 (both are marked as active development) – Raven Sep 18 '15 at 10:52
  • Only one indicates specific support for Windows 10. – Ramhound Sep 18 '15 at 11:07
  • upgrading to 5.0.4 did not solve the issue (weren't the Win10 support related to guest as opposed to host which is my case?) – Raven Sep 18 '15 at 11:28
  • confirm that your CPUs virtualization extensions are enabled in BIOS. – Frank Thomas Sep 18 '15 at 12:52

It is almost guaranteed that Hyper-V has been (re-)enabled.

Go to control panel and turn it off as per the photo.

Do make sure you have the latest VirtualBox as Windows 10 is not supported in versions before 5.x.

enter image description here

  • Also solves the issue with Windows 8.1 – nidomiro Mar 2 '16 at 10:22
  • Sorry for the old topic resurrect, but I don't have the Hyper-V option in the above dialog, is there any alternative? Thanks! – Roy Tang Jul 16 '16 at 16:42
  • Which windows version? – brianlmerritt Jul 16 '16 at 16:43
  • Still working for virtualbox 6.0 – Spears May 8 at 18:57
  • Thanks - have updated – brianlmerritt May 9 at 11:14

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