Before downloading, ensure your Mac supports this operating system: Late 2009 or later MacBook: Late 2009 or later MacBook Pro: Mid 2010 or later MacBook Air: Late 2010 or later Mac Mini: Mid 2010 or later Mac Pro: Mid 2010 or later Minimum Specs: 2GB Memory, 8.8GB storage available. 4. How to Create a Bootable USB Drive (Clean Install)
To download and install , you should use the official Apple Support website. Apple provides older macOS versions as disk image files (.dmg) because they are often no longer available directly in the App Store search. 1. Download the Installer
Disclaimer: As of 2026, Apple no longer provides security updates for macOS 10.12.6. Using an outdated operating system can expose your computer to security vulnerabilities. It is highly recommended to upgrade to a supported macOS version if your hardware allows.
This method downloads InstallOS.dmg to your Downloads folder. When opened, you will find InstallOS.pkg inside. Double-click this package to run the installer—contrary to what the name might suggest, this does not immediately install the operating system. Instead, it extracts and places the full Install macOS Sierra.app (approximately 5.03 GB) into your Applications folder. Only after this extraction is complete can you proceed with the actual installation.
sudo date 0101010119
Press Enter, type your Mac's administrator password, and press Enter again. Type Y to confirm that you want to erase the drive.
During its supported lifecycle, Sierra received numerous security updates addressing critical vulnerabilities including Spectre and Meltdown patches in early 2018. While these updates remain installed on properly maintained Sierra systems, newer vulnerabilities discovered after 2020 remain unpatched.
"This copy of the Install macOS Sierra application is damaged"
Open and paste the following command: sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/SierraInstaller --applicationpath /Applications/Install\ macOS\ Sierra.app