Solving Display Issue with Kubuntu 20.04 in Virtualbox

Kubuntu Virtualbox Settings

I must not be the only one with this problem, so I decided to write down this solution to help others. After using Ubuntu 20.04 for almost two weeks and being very happy with it I could resist the temptation to test some Ubuntu-based distros in Virtualbox. Most of them work flawlessly with the exception of Kubuntu 20.04. Kubuntu would always boot with 800x600 resolution. And every time I changed the settings to a higher resolution Kubuntu would revert back to that low resolution display.

I thought the issue would resolve by installing the Virtualbox Guest Additions, however the problem persisted.

After trying different settings without success I changed the Graphic Controller in Kubuntu Virtualbox Settings to VBoxVGA (see the picture above). Of course as you can see in that picture Virtualbox fires a warning of Invalid settings detected.

But this "invalid setting" solves the issue at least partially. Now Kubuntu can resize to different resolution from Kubuntu System Settings and persist that choice.

However the Virtualbox warning is actually not overriden because the display will not automatically resize at the VM level, for example full screen display is not possible. So it remains a partial solution.

Let's hope this issue will be solved soon, but at least Kubuntu is now usable.