I read that if a machine has Mojave 10.14 and one wants to return to ElCapitan/Sierra one needs to use an installer rather than erase and clone (w/ CCC) as Mojave would have re-written the firmware and changed to APFS and only using an older installer would change those things back.
Asking for confirmation, thanks!
MacBookAir
icwvx wrote:
I read that if a machine has Mojave 10.14 and one wants to return to ElCapitan/Sierra one needs to use an installer rather than erase and clone (w/ CCC) as Mojave would have re-written the firmware and changed to APFS and only using an older installer would change those things back.
Asking for confirmation, thanks!
MacBookAir
Revert your Mac to a previous macOS version - Apple Support
Restore your Mac from a backup - Apple Support
How to reinstall macOS from macOS Recovery - Apple Support
Downgrading is tricky.
You can backup your drive, erase that drive, install the older macOS you want and then migrate your data back from the backup to that drive.
The issue is that some of the data (such as photos, notes, eMail, etc.) will have been updated to work with the later version of macOS and may not work with the old version.
Thanks for the comments-
I just purchased a MBA w/ Mojave, used.
The programs I want to use are 32bit and cloned along w/ ElCapitan using CCC to an external.
I thought start the MBA from the external and use CCC to erase the MBA internal and clone the external contents.
return to ElCapitan/Sierra
