Powering off Guest without Graphics Controller causes Unresponsive Behavior -> fixed in 6.0.8 and 5.2.30
I have set the following options on Virtual Machine(s):
Graphics Controller: None
Graphics Memory: 0 MB
Powering off a machine will cause VirtualBox 6.0.6 to behave erratically and unresponsively. Configuring the guest with 5MB Video Memory and a Graphics Controller will allow proper function.
VirtualBox starts the guest again, and reports a memory error, where I have to end the process to fix this issue. I attempted to power off a couple dozen Headless Virtual Machines at once and my Host hung from attempting to restart the Virtual Machines. They also opened up the interface.
I am also having an issue where clicking "Show" on a guest without a Graphics Controller causes issues.
Downgraded to VirtualBox 6.0.4 to fix this issue on a production server. Multiple Virtual Machines power off as expected.
Perhaps configuring a guest with "invalid settings" may be the issue, but I have had no issues with running a guest without a graphics controller. I am running a full box with 200+ machines where I believe there may be unnecessary overhead with a Graphics Adapter.