You should only download the installer from official sources to ensure it is secure and complete. Mac App Store: You can find macOS High Sierra on the Web Browser: If the App Store link doesn't open, Apple Support provides direct download links for older macOS versions. Verification:
macOS High Sierra 10.13.6 full installer - Apple Support Community Macos High Sierra 10.13.6.iso
Because Apple provides the OS as an .app installer via the Mac App Store, getting an .iso usually requires a few extra steps: You should only download the installer from official
. It often redirects to the Mac App Store but may only work if your current Mac is compatible with High Sierra. Direct Browser Downloads : Older versions can sometimes be downloaded directly as files from the Apple Downloads Server How to Create a Bootable USB Installer It often redirects to the Mac App Store
hdiutil attach /tmp/HighSierra.dmg -noverify -mountpoint /Volumes/macOS