softwareupdate --fetch-full-installer --full-installer-version 10.15.7 Wait 20-30 minutes. The installer will appear in your /Applications folder named Install macOS Catalina.app . Use Terminal commands to convert the .app into a .iso .
# Create a blank DMG (temporary) hdiutil create -o /tmp/Catalina -size 8500m -volname Catalina -layout SPUD -fs HFS+J hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina Create a bootable installer inside the DMG (this takes 15 minutes) sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina --nointeraction Unmount the DMG hdiutil detach /Volumes/Install\ macOS\ Catalina Convert the DMG to ISO (CDR) hdiutil convert /tmp/Catalina.dmg -format UDTO -o /tmp/Catalina.iso Rename and move to desktop mv /tmp/Catalina.iso.cdr ~/Desktop/macOS_Catalina_10.15.7.iso Clean up rm /tmp/Catalina.dmg macos catalina 10157 iso download new
| Safe Indicators | Danger Signs | | :--- | :--- | | SHA-1 checksum provided | Cracked/activated claims | | Downloaded from Internet Archive (user @arm64) | Password-protected ZIP files | | File size exactly 8.8GB - 9.0GB | .exe or .dmg inside the download | | Published by known VM youtubers (Techsviewer, etc.) | Requests for payment or survey | # Create a blank DMG (temporary) hdiutil create
Catalina 10.15.7 is an old OS. After installing, consider disabling SIP (System Integrity Protection) only if needed for legacy software, and never expose the VM directly to the internet. Need help? Leave a comment below. For automated builders, check out GitHub scripts like macos-guest-virtualbox.sh – they automate the ISO creation from Apple’s servers. Stay safe and happy virtualizing. Leave a comment below
Last Updated: October 2024