Type the following command and press Enter: softwareupdate --fetch-full-installer --full-installer-version 10.13.6
The App Store delivers an .app package. You can convert it to a DMG using Terminal: download macos high sierra 10136 dmg mac top
(Note: You will need to type your Mac's administrator password when prompted). Detach the completed volume from your system: hdiutil detach /Volumes/Install\ macOS\ High\ Sierra Use code with caution. Type the following command and press Enter: softwareupdate
Bookmark this page. As Apple removes old installers from the App Store, these "top" methods become your only lifeline for legacy macOS versions. Good luck, and happy computing. and happy computing.