I need to upgrade my MacBook Pro 15 inch (2012) OS X from 10.11.6 to 10.13.6 or later.
However, I have downloaded several updates for 10.13 all the way down to 10.12.6 and in every case it says I need to have a prior operation system such as 10.12 for 10.12.6 to be installed.
In other words I can't seem to find an OS X system that I can install because I don't have the latest system for the update. So are all these OS systems updates only that require a previous version? Apple's download website just shows updates.
Where can I find a complete new OS to download so I can apply updates?