Rolling Back O.S.
 

My '09 Mac Pro needed to be replaced so I ordered a Mac Mini.
It was my understanding that Catalina could be rolled back to Mojave.
I sent the computer to OWC for a RAM upgrade and the O.S. rollback.
They called to say they couldn't roll it back.
Has anyone done this successfully, or sent it to someone else to do the work?
I did try to buy a mini with Mojave installed but couldn't find any.
I work in sound to pic so don't want to jump through the hoops that Catalina requires.
Thanks for any help,
JJ

Re: Rolling Back O.S.
 

Which model exactly? Go to Apple menu, About This Mac, System Report and from there tell us the Model Identifier that you can see from Hardware Overview

Re: Rolling Back O.S.
 

As far as I know all Mac Minis should be able to run with Mojave so just download installer from App Store, create a bootable USB installer (google for instructions), then wipe the hard drive and install.

Re: Rolling Back O.S.
 

Janne,

The computer is being shipped back to me so can't access the model identifier.

Re: Rolling Back O.S.
 

Well once you have it back you can do it yourself. Just have 16GB or larger USB stick ready

Re: Rolling Back O.S.
 

I'll give it a try. Surprised that OWC couldn't do it..

Re: Rolling Back O.S.
 

Too much manual work. T2 chip makes it tough to just clone a drive from old copy. Need to actually install it by hand. While you wait for your mini to arrive, you could also do some research regarding that T2 thing

Re: Rolling Back O.S.
 

Will do research. Thanks for your help.
John

Re: Rolling Back O.S.
 

No problem.

With that said, what you are going to do I have not done myself. But it should be possible. Worst case scenario you will do a clean install of latest Catalina and have to deal with it :cool:

Re: Rolling Back O.S.
 

I got one a month or so ago and I installed Mojave on it. Using a USB stick.

I think I did have to first go into Recovery and do a few things to allow it. I'm sorry I can't remember the specifics but plenty of info out there. Wasn't hard.

Re: Rolling Back O.S.
 

Yeah. I was a little interested about this so did some research. Have no T2 hardware here though, so cannot test.

Here's what you need to do, after you have created that bootable USB installer.

• boot into recovery mode (command+R while booting)
• in the menu bar, click utilities > startup security utility
• select admin account and enter password
• under "external boot" select "allow booting from external media"
• close the utility and restart the computer holding option key
• select your USB installer thumb drive
• when it boots it'll say "software update is required to use this startup disk"
• make sure you're connected to wifi, then select download. let it download. it will automatically reboot
• on the second reboot, hold down option and select the USB installer thumb drive again
• it will show the apple logo couple of times before the installer starts

This is how you should get your USB installer working with T2

Re: Rolling Back O.S.
 

Yes.
This is also needed for making external bootable clones.

Re: Rolling Back O.S. FWIW
 

Just rolled back a 2019 iMac to Mojave. No T2 chip. Had to use a usb 2.0 drive. For some reason boot drive with a 3.0 was undetectable

Re: Rolling Back O.S. FWIW
 

Yes. I’ve had this problem before too. Couldn’t for the life of me work out why.

Turns out, it’s dependant on the type of USB3 enclosure you’re using. If you do a web search you’ll find a bit of info pertaining to the issue.

Re: Rolling Back O.S.
 

I manage over 100 Macs for a University Music school here in London and just want to point out somethings from my latest experience:
1- the utilities security enable external boot only applied to Macs on sierra/ high sierra this wasn’t a necessary step with clean installs of Mojave it was an added security measure from apple in sierra/ high sierra.
2- If your mac is shipped with Catalina you wont be able to rollback to Mojave. This is based on my just having imaged 36 new mac minis in 2 of our mac labs.
3- target disk mode wont work using an original apple usbc cables only 3rd party cables still work. So carbon copy cloner running from an external drive worked fine for me.
4- Catalina will not make an older mac faster. Apples design model is to force you into buying new machines so I highly doubt the person who posted here that his iMac seemed faster because of the os update to Catalina is correct. He probably had improved performance from doing a clean install as wiping the disk and reinstalling will improve performance as bugs and permissions errors are put right or his mac was never configured properly. So I wouldn’t recommend that older mac users to rush into an OS upgrade based on that info.


Sent from my iPhone using Tapatalk