Your Mac will open the Software Update pane or start downloading the installer file.
Clicking the Sierra link there will open the App Store to a hidden page where you can click "Download." 3. Alternative: Direct DMG Download
Disconnect your Mac from the internet. Open Terminal during the boot installation process and change your system clock back to a year close to the software's release (e.g., type date 1015121517 to set the date to October 15, 2017). Restart the installation. "An error occurred while preparing the installation" download macos 1012 sierra full
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Press Enter, enter your password, and wait for the process to finish. Important Safety Tips Your Mac will open the Software Update pane
Note: You must perform this extraction process on a compatible Mac running a version of macOS that can read the package file. Method 2: Download Using the Mac App Store
Turn on the Mac and immediately press and hold the key. Release the key when you see the startup manager screen. Open Terminal during the boot installation process and
Press Enter, type your password, and wait for the process to complete. A Note on Security
Before downloading macOS 10.12 Sierra, ensure that your Mac meets the system requirements: