
Head over to the VirtualBox downloads page, grab the VirtualBox Oracle VM VirtualBox Extension Pack, double click the extension pack file (which has the vbox-extpack extension) and it should open with VirtualBox, allowing you to install it. It means the machine you tried to run was installed with VirtualBox Extension Pack support, so it needs this to run. The virtual machine 'Your machine name' has terminated unexpectedly during startup with exit code 1 (0x1). You have to select a pre-configured size.

For example, the screen resizing just shows a black screen when you resize the window or go to full screen. I have also found that the guest add-on does not work properly in 20.04 under 6.1. The error shown in a dialog box when upgrading from the Ubuntu repositories VirtualBox to the Oracle-provided VirtualBox: Then, click on Machine > New Now, type in a name for the VM, select Linux from the Type dropdown menu, and Ubuntu (64-bit) from the Version dropdown menu. Once I disabled the audio support, I was able to install Ubuntu 20.04 on VirtualBox 6.1 on OSX 10.15.6 (Catalina). This also applies to those using Ubuntu-based Linux distributions, like Linux Mint, elementary OS and Pop!_OS.

This article explains how to properly upgrade to VirtualBox downloaded from Oracle (either by downloading it from the VirtualBox website, or installed from the Oracle VirtualBox repository) when you have the Ubuntu repositories version of VirtualBox installed on your system. But when I upgraded to VirtualBox 6.1 downloaded from the Oracle VirtualBox website, I noticed I couldn't start any virtual machine anymore, receiving an error. When I upgraded to Ubuntu 19.10 I installed VirtualBox from the Ubuntu repositories since it was the same version as the one provided by Oracle anyway.
