Select (or Reinstall macOS ) from the Utilities menu. Click Continue and agree to the license terms.
Launched in 2016 as the first version of macOS after the rebranding from OS X, Sierra introduced several key features that are still appreciated today: download macos sierra 1012 dmg file install
From the macOS Utilities window, select and click Continue . Select (or Reinstall macOS ) from the Utilities menu