Mac OS X Yosemite 10.10.5 Download DMG: The Ultimate Guide Released in August 2015, macOS 10.10.5 was the final "victory lap" for the Yosemite era. It remains a vital operating system for users of older Mac hardware who need a stable, refined version of the "flat design" overhaul that Yosemite introduced. Whether you are reviving an old MacBook or need a bootable installer for troubleshooting, finding a clean is the first step. Why Users Still Download Yosemite 10.10.5