After I upgrade my VirtualBox on macOS(Big Sur) to the lateset version “6.1.18”, I cannot start any VMs from it. The Following error is reported:

Kernel Driver Not Installed (rc=-1908)

I find the solution here.

Go to “Security & Privacy -> General”, click the “lock” icon and open it, then click the “Allow” button of “System software from developer ‘Oracle America, Inc.’ was blocked from loading”.

Restart MacOS. Now I can start VM properly.

But why I didn’t encounter such issues before? If it’s caused by permission is denied by macOS, I should encounter it every time after I upgrade VirtualBox.