I am running a Mac mini late 2014 on High Sierra 10.13.6 and want to downgrade back to original OS 10.10.5 as several needed software apps quit working.
I need a way to reinstall, but can't seem to find anything other than "upgrades"
Going back requires a good backup of the Mac Mini from before you upgraded the macOS.
Then it requires using macOS Recovery Mode to completely wipe the Internal drive and reinstall macOS.
To get older macOS versions, see > https://support.apple.com/en-us/HT211683
To Erase and Reinstall your Mac Mini, see > https://support.apple.com/en-us/HT4718
IMHO it would be better for security reasons, to forge ahead with the macOS Upgrades and then upgrade or replace those old out dated third party software app's.
Going back requires a good backup of the Mac Mini from before you upgraded the macOS.
Then it requires using macOS Recovery Mode to completely wipe the Internal drive and reinstall macOS.
To get older macOS versions, see > https://support.apple.com/en-us/HT211683
To Erase and Reinstall your Mac Mini, see > https://support.apple.com/en-us/HT4718
IMHO it would be better for security reasons, to forge ahead with the macOS Upgrades and then upgrade or replace those old out dated third party software app's.
To reinstall the oldest available version in macOS Recovery, see > https://support.apple.com/en-us/HT201314
Or optionally make a 10.11 El Capitan Bootable Installer, as per > https://support.apple.com/en-us/HT201372
In either case Recovery or Bootable Installer, you will need to erase the internal hard drive and then install that version.
The only OS version that comes up is OS X 10.15, higher than what is on it now OS X 10.13.6
So I am still looking for the original OS installer.
OSX Yosemite 10.10.5 downgrade
