Third-party browsers (Chrome/Firefox) often block the direct download of Apple files or fail to redirect to the App Store. Terminal commands

As of May 2026, Apple no longer signs High Sierra for clean internet recovery. If you do not save this DMG today on an external drive, you may lose the ability to reinstalling on legacy hardware forever. Download it now, store it exclusively, and keep a legacy Mac alive.

Apple provides specific paths depending on whether you need a direct (typically for older OS versions) or an App Store installer macOS Sierra (10.12) DMG

This method forces Apple’s catalog to give you the exclusive DMG file directly: