[ubuntu] Unable to upgrade VirtualBox

Hi all,

VirtualBox 6.0
Host OS - Ubuntu 18.04

This is a spare desktop PC, having NOT been run for about a month. On starting VirtualBox I'm asked to upgrade to a new version of VirtualBox. On clicking to accept it finally a warning popupThis is NOT the first time I'm asked to upgrade VirtualBox on this PC but it is my first time encountering this problem.

I have been searching a while on Internet discovering several links having similar problem. Please advise how to fix it.

Thanks

Regards
satimis