MacOS 10.13 back to OSX Mountain Lion on sep. drive?

[Lesser Evets]

I'm trying to create a second drive with a legacy OS, and I am having problems that seem ridiculous.
Am I missing something in this process?

Computer : MAC MINI 2012 i7
Int. Drives: 1TB SSD w/10.13 + 256GB SSD w/nothing (hope to install OSX Mtn. Lion)
Thumbdrive: 16GB Toshiba with OSX Mtn. Lion disk image installed on it

OK. What I want to do is get the 256SSD reformatted with MOUNTAIN LION.

Problem: Restarting with OPTION held down always gives me errors and crashes the computer before the Thumbdrive Man. Lion disk can start up.

• I downloaded Mountain Lion's installer
• Found contents, went into shared folder
• Used disk image to create thumb drive disk
• Thumbdrive disk has Install OS X Mountain Lion/Library/Packages/System

Is Mountain Lion too far back? Is there something missing in this process? I really need help to figure this out. I'm trying Mavericks next, to see if Men. Lion is too old for this mini. Thanks for any help.

 

[glawrie]

Sounds like you have a more modern OS installed on the 1TB. Have you tried inserting thumb drive while booted into that and setting the startup disk via system preferences? If it is a legit boot volume thumb drive should show up in that dialog - if it doesn't then possibly something amiss with your thumb drive installer setup.

 

[treekram]

The 2012 Mini was introduced after Mountain Lion was introduced and it looks like you would need 10.8.2 or a Mountain Lion build 12B2080 or higher. The Lion installer may show the initial screen, but it should not install on the 2012 Mini. You might want to try Internet Recovery Option-Cmd-R - that's supposed install the version "that came with your Mac, or the version closest to it that is still available." Whether this means the earliest OS that came with the 2012 Mini or the specific OS version that was originally put on your Mini, I'm not clear about that.
https://support.apple.com/en-us/HT204904

But like post #2, I would think something with the flash drive or the installer setup is more likely the issue. With Mavericks, you can use the createinstallermedia option, which is more clear-cut.

 

[Fishrrman]

My 2012 Mac Mini i7 came with OS 10.8.2 as the "base OS". I believe this was a customized version of 10.8.2 to work with the Mini.

Later upgrades to Mountain Lion (i.e., 10.8.3, 10.8.4, etc.) work fine.

BUT...
IF you're trying to boot it with a copy of the Mountain Lion installer that is "previous" to this, it will probably crash.

Could this be your problem?

You need a copy of the Mountain Lion installer that is "10.8.3 or later" -- IF such a thing exists.

You MIGHT have to go to "unauthorized downloading sources" in order to find one.
I would not be concerned about going to such places if that's what I needed.
One has to do, what "one has to do"...