What is the of the Mac you are installing Sierra on? Are you downloading this file using a Mac or a Windows PC ? Share public link
Many Macs from 2009–2015 run best on Sierra or High Sierra. download macos sierra 1012 dmg file install
Apple provides direct HTTP download endpoints for older operating systems via their support frameworks. What is the of the Mac you are installing Sierra on
Double-click the downloaded InstallOS.dmg file to mount it. download macos sierra 1012 dmg file install
If you want, I can:
This guide provides verified download paths, installation requirements, and step-by-step instructions to create bootable media using a macOS Sierra 10.12 DMG file. System Requirements for macOS Sierra