Catalina downgrade to El Capitan?

[ChaLiWang]

Some specific reasons, I have to downgrade my devices macOS from Catalna to El Capitan.
I have 2 devices
1. Macbook Pro(Mid-2015)
2. Mac Mini(2018)

I made a bootable USB flash with Capitan inside and can downgrade the macOS to El Capitan for Macbook. But the same bootable flash and process, I got the error message when I do it for Mac Mini. The error message is " a software update is required to use this startup disk"

Any one have a clue? Thanks

[Hugonaut]

firmware comes to mind

[dwenger]

Hi @ChaLiWang,

El Capitan isn't supported for the 2018 Mac Mini. The following article breaks down the supported hardware for each major macOS release. https://support.apple.com/en-us/HT201686

[dwenger]

I need to clarify a bit on my previous post. Apple only supports rolling back to the version your computer would have shipped with when that model was released. The system requirements listed in the linked article will show how old of hardware you'll be able to run certain versions of Mac operating systems on.

[ChaLiWang]

Apple only supports rolling back to the version your computer would have shipped with when that model was released.!

It means that if my mac mini shipped with Mojave. I can't downgrade it to even high sierra, sierra?

[dwenger]

Correct.

If you really want to run one of the macOS builds prior to what shipped on that hardware, a virtual machine might be worth a try.