I recently picked up a bunch of older Intel Macs that a client was disposing of, and needed to wipe them and instal an older version of macOS, such as Catalina, on them.
In order to do this, I wanted to build a couple of USB sticks with the macOS installer. I wanted the latest version of Catalina, 10.15.7 so tried to download it from Apple. The Mac App Store wouldn’t let me download it as it was not compatible with my Apple Silicon Mac.
Whilst Apple publishes download URLs for some older versions of macOS that can be downloaded directly, bypassing the Mac App Store, Catalina is not on this list. If you need to download anything from 10.7 Lion through to 10.12 Sierra, these links will sort you out:
Catalina however remained elusive.
After some searching, I found an excellent utility called MIST – macOS Installer Super Tool. This utility allows me to download macOS installers from 10.7.5 Lion, all the way up to the latest macOS Sequoia versions.
Now, the next step for me is to get the createinstallmedia command from the Catalina installer running on Apple Silicon
Good stuff. You might take this one step further and start using erase/install. We use it for not only wiping and reinstalling specific versions of MacOS, but upgrading to a specific version of MacOS that isn’t the latest.
We have started using it in our MDM called Mosyle for fresh wipes of older Macs. We are also using it to do manual upgrades where we don’t want to install the latest version of Sequoia for various reasons. It’s been way handier than using USB thumb drive installers.
You can check the project out here.
https://github.com/grahampugh/erase-install