The answer posted by bmike is far simpler and more practice, if your Mac can boot OS X installers from a flash drive and you have another Mac that can install the 'Install OS X El Capitan' application from the InstallMacOSX.dmg file downloaded from Apple.īelow are the steps to install Yosemite on your Mac.īefore following the steps posted below, you probably should post the output from the diskutil list disk0 command so your question. I realize this is a rather lengthly installation procedure. Finally, the Mountain Lion boot and recovery volumes are converted to free space and the Yosemite volume is expanded to reclaim this free space. Basically, you first install Mountain Lion on a new (clean) volume, then use Mountain Lion to install Yosemite on a different new (clean) volume. The two other downloads are OS X installers from Apple. One download is the installer for a third party disk partitioning tool called 'GPT fdisk'. You will need to download free installation files. Updated December 2019: Everything is up to date through macOS Catalina.Since you can boot to OS X Yosemite Recovery, you can install Yosemite without the aid of a DVD, flash drive or another Mac. If you have any more questions about reinstalling macOS on your Mac, let us know in the comments. How to set up and customize your Mac from scratch Questions? If you're starting from scratch, you'll need to set up your Mac from scratch.

Your Mac will now go through the normal macOS installation process, eventually restarting.

Enter your Apple ID and password if you're asked to, though you might not be.Click on the drive on which you wish to install macOS.How to reinstall macOS while in Recovery mode If you're running macOS High Sierra or later on a Mac with an SSD, your choices will be some form of APFS. Click on the format you want to use for your drive.Click on your startup disk in the Disk Utility sidebar.

How to access os x utilities