macOS Catalina
We advise waiting a while before updating your Mac to the new macOS version, Catalina, for two reasons: firstly it has bugs, which Apple is steadily fixing; secondly it introduces a security system which is causing problems for software which hasn’t been adapted to deal with it. At the time of writing, VirtualBox is an example. For more details, and some helpful links, see our computing.help page on macOS releases.