Original post: Virtualbox 6.1.x Windows-10 2004 Upgrade Problem Resolution
This is just a quick note that will hopefully save someone time.
When I upgraded Windows 10 (64-bit) from 1909 to 2004 I found that Virtualbox 6.1.x no longer worked properly. All of my guest instances (Ubuntu, Mint, etc.) failed to start. Specifically, they just hung with a blinking cursor and there were no errors in the logs.
There were no reports on this problem on the VirtualBox on Windows Hosts forum.
It turns out that when Windows 10 2004 is installed it enables the Windows Hypervisor Platform feature.
To check this setting run OptionalFeatures.exe from a Windows command shell. You'll see this:
The resolution to the hang problem is to disable this feature. Doing this is simple:
- Uncheck the Windows Hypervisor Platform checkbox (above).
- Reboot. Even though it's not indicated when you do step #1, a reboot is required to disable the feature.