Can you downgrade Mac OS on a brand new Mac?

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Can you downgrade Mac OS on a brand new Mac?

I just received a new Mac mini (Intel CPU) with Monterey installed. The software I am using does not support Monterey so I have attempted to downgrade to Catalina by following this article. So far, this is not working. I do have the T2 security chip and have enabled 'boot from external drive' so I don't think that is the issue.

I ran across a reference somewhere (can't find it now) stating you cannot downgrade a Mac past the OS it was shipped with. Is that true? I specifically purchased the Intel version of this mini knowing I'd need to downgrade.

Posted on Jan 11, 2022 7:46 AM

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Answer 1

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Matti Haveri

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Jan 11, 2022 7:59 AM in response to d7777

Try it although it might very well be limited to Monterey and up.

What does the Terminal "softwareupdate --list-full-installers" say about your download options? For my Mac mini 2018 that supports Mojave and up, it lists:

softwareupdate --list-full-installers

Finding available software

Software Update found the following full installers:

* Title: macOS Monterey, Version: 12.1, Size: 12157035487K

* Title: macOS Monterey, Version: 12.0.1, Size: 12128428704K

* Title: macOS Big Sur, Version: 11.6.2, Size: 12433351292K

* Title: macOS Big Sur, Version: 11.6.1, Size: 12428472512K

* Title: macOS Big Sur, Version: 11.6, Size: 12428553042K

* Title: macOS Big Sur, Version: 11.5.2, Size: 12440916552K

* Title: macOS Catalina, Version: 10.15.7, Size: 8248985973K

* Title: macOS Catalina, Version: 10.15.7, Size: 8248854894K

* Title: macOS Catalina, Version: 10.15.6, Size: 8248781171K

* Title: macOS Mojave, Version: 10.14.6, Size: 6038419486K

Then, if possible, download Monterey, Big Sur and Catalina full installer, make a bootable USB flash installer and try to boot them (after enabling external boot in the Recovery mode as you apparently already have done).

https://support.apple.com/en-us/HT210190

https://support.apple.com/en-us/HT201372

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Answer 2

Jan 11, 2022 8:52 AM in response to d7777

hmm... sounds like the Mac boots from Internet Recovery -- is there a spinning globe?

Internet Recovery: Shift-Option-Command-R during startup, you're offered the macOS that came with your Mac, or the closest version still available. If you use Option-Command-R during startup, in most cases you're offered the latest macOS that is compatible with your Mac. Otherwise you're offered the macOS that came with your Mac, or the closest version still available.

https://support.apple.com/en-us/HT204904

On the other hand, bootable USB flash drive: With my setup I make the bootable USB flash drive via the Terminal, shutdown the Mac, power on with Option pressed (just a reboot also works but needs correct timing with the Option key when the Mac chimes) and select the bootable USB flash drive and the Mac boots to that (with no network prompt).

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Answer 3

d7777 Author

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Jan 11, 2022 8:23 AM in response to Matti Haveri

Thanks for that command. I got the same result as you so it seems this mini does support Catalina.

Must be something else. Here is my specific error (sorry I don't have a screen shot handy): Upon booting from the USB drive, I get the window where I select what to boot from. At this point, I also select a wireless network and enter the password. After some whirling, I get what looks like a greyed out Recovery screen with the message that I need to 'select a network from the list' although no list is provided. The only options not greyed out are 'restart'. Is it possible a wired network connection is required to validate the OS I am attempting to boot from?

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Answer 4

d7777 Author

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Jan 11, 2022 10:50 AM in response to Matti Haveri

Well, it just will not boot from the USB drive. So I ran to the local Apple Store and they took a crack at it. Initially, they thought it would be easy to downgrade. But their first attempts are not working either. So they are keeping the Mac while they escalate further into their technical resources. I'll report back how this ends.

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Can you downgrade Mac OS on a brand new Mac?

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