As soon as the start-up chime plays, press the Option key (Alt). Step 1: Ensure the bootable USB flash drive is plugged into your Mac and restart the computer. How to Clean Install OS X Yosemite on Your Mac The OS X Yosemite bootable USB flash drive will be ready for use and you can start the clean installation process. Once the process completes, you will see the message ' Copy Complete. Do not interrupt the Terminal or eject the flash drive during the process. This will create the bootable USB flash drive.Please replace a single '-' with '-' when you enter the above command line in the terminal. Note: The code above has missing double dashes in the quotes. Sudo /Applications/Install OS X Yosemite.app/Contents/Resources/createinstallmedia -volume /Volumes/Untitled -applicationpath /Applications/Install OS X Yosemite.app -nointeraction You can do this by using the Time Machine feature in Mac OS X, or third-party software such as Carbon Copy Cloner.Ĭ) Create a bootable USB flash drive with a storage size of at least 8GB.ĭ) Download OS X 10.10 Yosemite Final from the Mac App Store and save it to the Applications folder – its default location. MacBook (Late 2008 Aluminium, or Early 2009 or newer)ī) Back up important data and settings (photos, videos, music files, documents and the like) on your Mac to an external hard drive.Supported OS X Yosemite devices and first stepsĪ) Ensure your Mac is compatible with OS X Yosemite. Apple macOS Sierra: How to reinstall the Mac operating systemīefore we begin the detailed process of clean installing OS X Yosemite on Macs, there are a few things you'll need to do first.

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