After I installed El Capitan on a MacBook Pro, I decided I wanted to have a copy of Yosemite on a separate partition. I downloaded Yosemite while running El Capitan and a message came up stating that I cannot install Yosemite over El Capitan because Yosemite is too old (similar to the iOS downgrade process). I didn't want to downgrade OS X though. Is there any way to install Yosemite on a separate partition while using El Capitan? At all?
Cannot install Yosemite on separate partition
Yes, but you'll have to make a bootable installer. Do you have an external drive or 8GB+ flash drive?
This is the support page you need: https://support.apple.com/en-ie/HT201372
You can make the bootable installer while in El Capitan - just follow the instructions above. Let me know if you then have any trouble setting up your new Yosemite partition.
In your case, assuming you've downloaded the Yosemite installer app and it's sitting in the Applications folder of your El Capitan partition, then:
- Erase your 8GB+ USB stick or whatever as Mac OS Extended (Journaled) and give it a name without spaces in it like YosemiteInstaller. I'll assume you use that name for the following Terminal command:
- sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/YosemiteInstaller --applicationpath /Applications/Install\ OS\ X\ Yosemite.app
- It may take quite some time to finish creating it, depending on the speed of your media but when it has, alt-boot into the bootloader and boot into the new YosemiteInstaller drive.
From there you should have no trouble installing onto the partition you prepared for Yosemite 🙂