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 ...

VirtualBox is great for testing out a new operating system, but your virtual machines probably aren't that special when you first set them up. Here are a few tips for making them much easier to ...

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 ...

When you start VirtualBox, you should see a screen like this. You don’t need to change anything yet; just click the “New” button in the top left corner. Now you need to tell VirtualBox what kind of OS ...