(Solved) VT-x is Not Available (verr_vmx_no_vmx) in Windows 10 – but Available for Oracle VirtualBox

When you get the error message “VT-x is not available (verr_vmx_no_vmx)” in Windows 10 or 8.1, follow the below steps to fix it. You may get “Failed to open a session for the virtual machine {VM Name}” message when you tried to power on a VM in VirtualBox which used to work fine earlier. I suddenly faced the same issue, and my most of the VMs could not be started.  Then found the cause and fixed it. Let me explain that here.

VT-x is not available (verr_vmx_no_vmx) in Windows 10

What is the Reason?

The Oracle VirtualBox software is not seeing the virtualization technology (VT-x) in the host Operating System, in this case, it is Windows 10. VT-x is a feature from BIOS and the processor support. In my example, it was working fine till recent time, and I did not do any changes inside the BIOS.

The Cause (for all scenarios)

  • VT-x is not enabled in the BIOS

You can eliminate this if you have not manually disabled VT-x in the BIOS in recent time. There is no reason why someone will go and disable the virtualization technology in the BIOS, but if you have done that for some strange reasons, enable the VT-x as shown in our guide.

  • The CPU doesn’t have VT-x support

I doubt this is applicable when you have a running Windows 10 64Bit on your computer. If you are using Windows 10 6Bit, surely your computer processor supports VT-x technology. So, you might have disabled it. If you disabled it, I’m not sure whether Windows 10 will boot. Anyhow, make sure that VT-x is enabled in the BIOS for these two causes.

  • Hyper-V virtualization is active in Windows 10.

This the reason for my case, and many of you too. I just enabled Hyper-V feature on my Windows 10 to install virtual machines for testing purpose.  Hyper-V and VMs in it worked well, but now VirtualBox is not opening virtual machines.

Testing the CPU technologies by the Intel tool said that the Vt-x is off as below (though it is enabled in the BIOS).

It Says VT Is Off

Also if you installed Microsoft Docker which uses Hyper-V virtualization technology, you may face the “vt-x is not available (verr_vmx_no_vmx)” issue with Oracle VirtualBox in Windows 10 or 8.1. In this case,e Microsoft recommends using the DockerToolbox which uses the VirtualBox technology instead of Hyper-V.

  • Check the Antivirus or Recently installed software

Some of the Antivirus (like Avast) or other programs might use the virtualization technology directly in the host computer. If they do, you should be able to disable them in the particular program settings. That should bring back the working virtual machines in Windows 10.

The Solution

The solutions worked for me is to remove the Hyper-V feature from my Windows 10. As of now, you can’t use the Hyper-V and Oracle VirtualBox on the same computer to host virtual machines.

Disable Hyper-V Feature from Control Panel.

Under Programs and setting, click on the “Turn Windows features on or off,” then select the Hyper-V platform to remove the Hyper-V feature. If you do not manage Hyper-V hosts on the network from your Windows 10 PC, you can remove the Hyper-V management console also. But, that Hyper-V management console doesn’t use the VT-x, the platform uses it. So, it depends on you to remove the entire features or only the Hyper-V platform.

Remove Hyper V

If you are a computer geek who likes command prompt, open the command prompt as Administrator and run the below command to remove Hyper-V feature.

dism.exe /Online /Disable-Feature:Microsoft-Hyper-V

Restart the machine to take effect.

After removing Hyper-V feature and restarted computer (without touching the BIOS), the Intel processor Identification utility said that Intel Virtualization Technology is enabled and supported as below.

VT X On After Reboot

Also, the VMs in VirtualBox started working as usual without any error such as “Failed to open a session for the virtual machine {VM Name}”

The Bonus Tip

If you have not installed Hyper-V feature recently or any other changes than the Windows update, then follow the below simple trick. If your VirtualBox Virtual machines stopped working with the same error message after the Windows update, then you need to enable the Hyper-V all features under the same place “Turn Windows features on or off” in Control Panel, then restart. After the restart, revisit the same place and disable all features of Hyper-V and restart. It is to enable and disable the feature to clear some bugs on VT-x caused by Windows update.

Hope this guide is helpful in troubleshooting the particular error message which prevents VMs from starting in Oracle VirtualBox.  The main culprit is Hyper-V, Docker or any other programs that use the VT-x technology directly all the time.

Do let me know in the comments area that which one caused the issue to you and how did you fix it.

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