The app sitting inside your Applications folder. Terminal Method
If you downloaded the official InstallOS.dmg from Apple's support site, follow these steps to turn it into a usable installation application: Double-click the downloaded file to mount it.
2 GB Required free storage: 8 GB for the installer + ~12 GB for the OS itself.
Use Disk Utility to format the drive as "Mac OS Extended (Journaled)".
https://support.apple.com/downloads/macos-yosemite-10-10-5 mac os x yosemite 1010 5 download dmg link
For non-developers, try this legacy command (works on Sierra or High Sierra):
Click , accept the licensing agreement, select your primary hard drive, and click Install . Your Mac will reboot to complete the setup. How to Create a Bootable USB Installer
: If you already have 10.10.x installed and only need to reach version 10.10.5, use this standalone update package (approx. 2.12 GB). Apple Support Installation & Deployment Extract the Installer : Double-click the downloaded file to open it. Run the
Mac OS X Yosemite (version 10.10) marked a major design shift for Apple, introducing a flat, translucent interface inspired by iOS 7. If you are looking for the official to revive an older Mac, create a bootable installer, or set up a virtual machine, finding a clean, safe source can be challenging. The app sitting inside your Applications folder
When you use the official link above, you will download a file named InstallOSX.dmg . This is not the final operating system installer; it is an installer for the installer. Follow these steps to extract the actual "Install OS X Yosemite.app":
That’s likely a stub installer – a small file that downloads the full 5 GB+ during installation. You need a full standalone DMG. Ignore stub versions; search for InstallMacOSX.dmg that is between 5.2 and 5.8 GB.
Follow the onscreen instructions. This action does not install the OS yet; it places the application into your Mac's Applications folder. Step 3: Run the OS X Yosemite Setup Navigate to your Applications folder. Double-click Install OS X Yosemite .
If the output doesn’t match, the file has been modified – do not use it. Use Disk Utility to format the drive as
Yosemite 10.10.5 is currently in a difficult stage of life. It can no longer run the latest versions of Chrome, Slack, or Microsoft Office efficiently due to API changes and security protocols. It does not support APFS file systems natively, meaning it is restricted to HFS+ drives.
For a safe download, avoid third-party "DMG" links found on search engines, as they often contain adware. Use the official Apple Support link to download the installer App, and use the Terminal command if you require bootable media.
Mac OS X 10.6.8 (Snow Leopard) or later installed to upgrade directly. Compatible Mac Models iMac: Mid-2007 or newer MacBook Aluminum: Late 2008 MacBook Polycarbonate: Late 2009 or newer MacBook Pro: Mid/Late 2007 or newer MacBook Air: Late 2008 or newer Mac Mini: Early 2009 or newer Mac Pro: Early 2008 or newer How to Convert the Apple Download into a Bootable DMG