VT-x is not available, but is enabled in BIOS
There are three common culprits for the type of error the user is seeing:
- VT-x is not enabled in the BIOS
- The CPU doesn't support VT-x
- Hyper-V virtualization is enabled in Windows
Since the user already eliminated the first two possible culprits, the next step is to open a command prompt as administrator and run the following command:
dism.exe /Online /Disable-Feature:Microsoft-Hyper-V
Afterwards, reboot the PC and try VirtualBox again.
After updating Windows 10 to "Fall Creators Update" I got the same issue. I resolved it by the following steps:
- Enable all features under "Hyper-V" in "Turn Windows features on or off".
- Restart.
- Disable all features under "Hyper-V" in "Turn Windows features on or off".
- Restart.
- Now VirtualBox is working again and it shows (64-bit) in its list of operating systems.
When I had this problem, VMWare Player gave a better diagnostic response than VirtualBox did when I tried to create a 64-bit virtual machine.
It said that my machine had the enterprise features Device Guard and Credential Guard enabled. I suppose they became enabled when I ran MalwareBytes; I can't think of any other change I made.
VMWare Player pointed me to a page called Manage Windows Defender Credential Guard. That page has a bunch of stuff about Group Policy Manager settings and the like, which of course are irrelevant to a W10 HOME installation.
In turn, that page pointed me to the Device Guard and Credential Guard hardware readiness tool, a PowerShell tool for enabling and disabling this feature set on servers.
Running that tool in a Run-As-Administrator power shell and giving this command
.\DG_Readiness_Tool_v3.5.ps1 -Disable -AutoReboot
took me through the process of disabling those features.
And I have virtualization capability back.