If you cannot open the guest session and get a VERR_NOT_FOUND VirtualBox error, follow the tips, solutions, and workarounds mentioned below. Check if “VBoxGuestAdditions.iso”n exists Insert Guest ...

It is the first thing you need to fix the issue as stated above. For that, you need to run the virtual machine showing the error and go to the Devices > Install Guest ...

Running multiple operating systems side-by-side gives you the chance to test applications, run platform-specific software, and tons more without ever rebooting. It's also extremely cool. Here's how to ...