[ubuntu] Ubuntu 20.04 upgrade

Hi,

I am running Ubuntu 20.04 via Hypervisor on a virtual machine and have tried several times without success to make this update/upgrade. Result is a blank (black) virtual machine screen.

The revert option to a previous checkpoint also doesn't bring me back to a running Ubuntu, before I reinstall everything and choose not to upgrade does anyone have any advice please??

Kind regards,

Scubasteve63