How to revert to a previous version of macOS
I don't need to do this right now, but I'm just trying to understand the process.
If someone updates their macOS (e.g. 10.14 to 10.15) and then decides they want to revert to the previous version (e.g. 10.15 to 10.14), what's the best way?
(In these examples, I'm only looking at the option of erasing and reinstalling a copy of macOS; I appreciate there are other issues such as some applications may have already been updated to work with 10.15.)
The key issue is this: having installed (in this example, 10.15), they need to erase their internal drive and install 10.14, but:
(1) Booting up with Command (⌘) - R will install the latest macOS that was installed on the Mac (10.15).
(2) Booting up with Option (⌥) - Command (⌘) – R will install the latest macOS that is compatible with your Mac (10.15)
(3) Booting up with Shift - Option (⌥) - Command (⌘) - R will install the macOS that came with the Mac, or the version closest to it that is still available. Eg. 10.12.
So none of these is the 10.14 wanted.
So is the only way to achieve 10.14 in this example option three, and then upgrade from 10.12 to 10.14?
(Obviously it the user has a Time Machine backup that was taken before the upgrade to 10.15 they could restore that instead after erasing the contents on the internal drive to remove the partitions on it.)
