Downloading macOS High Sierra 10.13.5 Image File: A Step-by-Step Guide

macOS High Sierra 10.13.5 (not "10135") is an older version from 2018. Apple no longer digitally signs it, so it may not install easily on modern Macs.

Mist Utility: For users on newer Macs (Monterey or later), the Mist tool on GitHub can bypass App Store limitations to download older macOS firmwares and installers directly from Apple's servers. Creating an Image File (DMG or ISO)

ISO for Virtual Machines: After creating a bootable DMG or USB, you can use Disk Utility’s "Convert" feature to change the format to a CD/DVD Master (.cdr), which can be renamed to .iso for use in software like VirtualBox or VMware. Troubleshooting Common Issues