Downgrading El Capitan to Mountain Lion

[Karl_Malone]

Hey guys, I'm pulling my hair over this but would anyone know how to downgrade from El Capitan to Mountain Lion? I've found a few tutorials but most of them want to use a Time Machine backup which I don't have. I figured I might be able to boot from a USB drive but I get stuck because the disk utility on El Capitan is completely different than the ones I find in the tutorials. Basically I can't seem to find the "Source" or "Destination" options like the ones mentioned on these instructions: http://www.hongkiat.com/blog/clean-install-mountain-lion/
However I'm wondering now if it's even possible to install Mountain Lion from a USB drive. I'm pretty stuck and any help would be much appreciated. Thanks!!

 

[chscag]

Not enough information: Which Mac do you have, year and model? Have you ever purchased Mountain Lion from the Mac App Store?

 

[Karl_Malone]

Not enough information: Which Mac do you have, year and model? Have you ever purchased Mountain Lion from the Mac App Store?

Sorry, it's a Mid 2009 Macbook Pro. I have purchased Mountain Lion, I have a digital copy of it right now.

 

[chscag]

If you have previously purchased Mountain Lion, you can download it again from the Mac App Store and build a bootable USB flash drive with it. After that, you should be able to wipe out (erase) El Capitan, boot with the flash drive and install Mountain Lion. Make sure you backup your data first. You can find instructions on how to make a bootable Mountain Lion flash drive on the net or from Macworld Magazine.

 

[Karl_Malone]

Hmmm, well that's the problem. All the tutorials I've seen involve using a disk utility that is different (older) than the one that is on El Capitan. When I get to the part that involves the "Source" and "Destination" I am a bit lost because those options simply aren't available on the Disk Utility I have (which is a simpler layout). Such as the ones shown on this http://www.hongkiat.com/blog/clean-install-mountain-lion/

 

[dtravis7]

The options are there but are not out in the open like with previous versions of Disk Utility. Let me see if I can find you a tutorial on the new (El Capitan) Disk Utility and post it here for you.


One warning just so you know, I have my early 2008 iMac partitioned 1/2 Mountain Lion and 1/2 El Capitan. The internet has so changed that now using Safari which I love causes many issues with Facebook and many other sites. Sure I can use Firefox or Chrome, but really prefer Safari. I was shocked just how much even Mountain Lion is affected by todays internet. The main reason I need ML on is it's the last version of OSX that supports some video conversion Applications that I love and nothing new I have tried is equal to what I have been using for years, so I keep it around for that use.

 

[gsahli]

Make a bootable OS X installer:
https://support.apple.com/en-us/HT201372

 

[mad_macs]

Just curious about the dualboot. Are you using a bootloader that is selectable or are you just holding option at boot time to select?

 

[Karl_Malone]

Hey guys, thanks for all the help I really appreciate it. I was actually able to use someone else's macbook (using an older OSX version) and was able to make the installer from there. Worked like a charm. Just to mention though, I was downgrading because Pro Tools and my other various audio workshop programs are not supported by El Capitan. My dumb mistake by not checking before I upgraded. Anyways, thanks again guys.

 

[toMACsh]

My dumb mistake by not checking before I upgraded. Anyways, thanks again guys.

Always make sure you have the ball before going up for a dunk.

 

[tcrossnz]

Hey guys I'm stuck in a similar situation.
I have a new Macbook Pro (MacBookPro8,3 - Mid 2015) that came with El Capitan installed.
I also want to remove this OS and install Mountain Lion.

I can't use the time machine method because this Macbook only had El Capitan OS on it.
What's the best way to install Mountain Lion? I've purchased a licence from Apple and have it in my Macstore account.

Many thanks!
Tom

 

[pigoo3]

I have a new Macbook Pro (MacBookPro8,3 - Mid 2015) that came with El Capitan installed.

Need to know exactly what model MacBook Pro you have. It can't be a "MacBook Pro 8,3 - Mid 2015"…because MacBook Pro 8,3's are either from "Early 2011" or "Late 2011".

MacBook Pro's from "Mid 2015" are either MacBook Pro 11,4 or MacBook Pro 11,5.

- Nick

 

[harryb2448]

All 2015 series are 12 numerals.

 

[tcrossnz]

apologies I typed the wrong model number that's my old Macbook. My new Macbook is 11,5

 

[pigoo3]

apologies I typed the wrong model number that's my old Macbook. My new Macbook is 11,5

Thanks for the additional info.

Short answer…can't do it. The "oldest" OS a Mid-2015 MacBook Pro 11,5 can run is Yosemite (OS 10.10). Mountain Lion is OS 10.8…too old.

Sorry,

- Nick

 

[tcrossnz]

oh that's a shame! How come it won't work?

 

[pigoo3]

oh that's a shame! How come it won't work?

Just the way it is. As a general rule. An Apple model computer can't run an OS version older than it originally shipped with. Your mid-2015 MacBook Pro shipped with Yosemite originally (10.10). Mountain Lion (10.8) is a good bit older…thus not compatible with a 2015 MBP.

If you REALLY need to run Mountain Lion. Need to get an older Apple computer (kind of like the one you had).

- Nick

 

[tcrossnz]

ok thanks for your help Nick

 

[pigoo3]

ok thanks for your help Nick

Good deal. You're welcome.

- Nick

 

[feralicious]

Just the way it is. As a general rule. An Apple model computer can't run an OS version older than it originally shipped with. Your mid-2015 MacBook Pro shipped with Yosemite originally (10.10). Mountain Lion (10.8) is a good bit older…thus not compatible with a 2015 MBP.

If you REALLY need to run Mountain Lion. Need to get an older Apple computer (kind of like the one you had).

- Nick

Do you know what the technical reason is? What happens if you try to install an older version?