Is there a way to know which macOS or OS X version was initially "clean-installed" on a particular Mac computer? (Assuming major or minor OS updates may have been installed later.)

Please note that I don't want to know which OS version originally shipped with the Mac (in brand new condition), as MacTracker has already that info. I'd just like to know which OS version was used the last time someone made a clean install, reformatted the drive, etc.

1 Answer 1


I've Looked for clues in /Library/Receipts/InstallHistory.plist

On a few computers I checked, they typically start with a "com.apple.pkg.OSInstall" package. It doesn't mention OS version, but scrolling down to most recently applied OS updates, and it may become clear what the OS version was by the updates.

BTW, all bets are off if the drive was cloned from another computer.

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