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The first post of this thread is a WikiPost and can be edited by anyone with the appropiate permissions. Your edits will be public.
Added new section to the WIKI page:
macos-iso: Automated macOS ISO Creation for Virtualization
macos-iso provides automated workflows (using GitHub Actions) to create bootable macOS installer ISOs for virtualization and USB use, supporting versions from Lion to Sequoia including Mavericks.
  • Uses GitHub Actions to automate ISO creation—no local script or Homebrew install required.
  • ISOs are built in the cloud and uploaded to GitHub Container Registry (GHCR) for easy download.
  • Supports installer apps from the Mac App Store or Apple.
  • Produces ISOs suitable for USB creation or virtual machines (VMware, Parallels, VirtualBox, QEMU, etc).
  • Supports both Intel and Apple Silicon Macs.
For instructions on triggering a build and downloading the resulting ISO, see the macos-iso GitHub page.
 
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You need at least 2GB of RAM to install Mountain Lion.
I have already tried that suggestion Bigwaff. Once the USB stick is inserted into 2007 with 6 GB memory, iMac a ‘No Entry’ symbol is imposed upon the file.
It seems a download from Mist on a APFS OSX effects the files in some way that makes it incompatible with the old Apple extended format. I am guessing. Whatever - it does not work.
 
I have already tried that suggestion Bigwaff. Once the USB stick is inserted into 2007 with 6 GB memory, iMac a ‘No Entry’ symbol is imposed upon the file.
It seems a download from Mist on a APFS OSX effects the files in some way that makes it incompatible with the old Apple extended format. I am guessing. Whatever - it does not work.
try this image:
Code:
brew install oras
oras pull ghcr.io/startergo/macos-iso:10.8-mountain-lion-dmg
 
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try this image:
Code:
brew install oras
oras pull ghcr.io/startergo/macos-iso:10.8-mountain-lion-dmg
Apologies for late reply startergo. Have managed to download and update Lion, Mountain Lion and Yosamite using the 2007 iMac with 2TB Samsung Evo SATA SSD installed to provide some speed. By various means I have managed to get OSX 10.6.8; OSX 10.7.5; OSX 10.8.5; and OSX 10.10.5, each installed on individual partitions and working properly using Combo updates to upgrade to latest available version.

These are now safely cloned to external HDD for future insurance.

This effort is justified as I periodically use Adobe CS5 to update legacy artwork. Also I need to use my Microtek M1 Scanner and Epson Photo 2400 A3 printer as the drivers are locked into various old systems. The glass-less Microtek M1 scanner has no consumer equal today. Epson scanners are inferior with glass between scanlight and 35mm film.

Snow Leopard and Lion can be updated without any trouble using Apple>Software Updates straight over the internet. These OSX were originally disk based installations. When the Apple installer system was introduced with Mountain Lion, Apple store access became paramout as did a pre-installed system for the new OSX to install over.

From OSX 10.8 forward, Apple Store does not recognise my Apple ID and also requires Safari for automatic Apple Store access. Safari is long deprecated and will not work. Neither will my Apple ID, so using Firefox is no answer. Using non-apple sources for OSX downloads re-introduces the Apple certificate authentication problem as you know.

I Have Home Brew installed on the 2019 iMac so will keep your code in my Notes for future use.

Thank you very much for your valuable contributions.
 
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