: macOS Sierra is "End of Life" and no longer receives official security updates. for a different macOS version or help troubleshooting a "damaged installer" error?
If you want to create a bootable installer for macOS Sierra 10.12, you'll need: Download Mac Os Sierra 10.12 Dmg
Once you've downloaded the InstallOS.dmg file, you can't just run it to upgrade. You first need to extract the actual "Install macOS Sierra" app: Double-click the downloaded file to mount it. : macOS Sierra is "End of Life" and
If you simply need an older app compatibility, consider (10.13) or Mojave (10.14) as they are slightly more secure while still supporting 32-bit apps. Download Mac Os Sierra 10.12 Dmg