: Double-click the downloaded InstallOS.dmg to mount it.
If the App Store link fails, open (Applications > Utilities) and run: Download Mac Os Sierra 10.12 Dmg
softwareupdate --list-full-installers
Once the download is complete, follow these steps to install: macOS Sierra | Specs, reviews and EoL info - InvGate : Double-click the downloaded InstallOS
Whenever possible, disconnect macOS Sierra systems from the public internet. open (Applications >
macOS Sierra generally supports MacBook and iMac models from late 2009 or later, and MacBook Air/Pro, Mac mini, and Mac Pro models from 2010 or later.
