I was wondering if someone could help me out. I am running Catalina but would like to install an older version os (sierra or el capitan) on an external and be able to boot from it. i have looked up some videos but I'm still having trouble. Any help would be really appreciated.
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installing older macOS on external HDD
- Thread starter crazmxican1
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See this. You should be able to select the external disk when you install. However, I would never attempt to do something like this unless I had (at least) one good clone of my internal disk, just in case something goes wrong.
support.apple.com
How to download and install macOS - Apple Support
Download and install current or previous versions of the Mac operating system on compatible Mac computers.
i DL'ed the installer and used Terminal utility to create a bootable but I'm getting the following message:
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app
Password:
sudo: /Applications/Install macOS Sierra.app/Contents/Resources/createinstallmedia: command not found
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app
Password:
sudo: /Applications/Install macOS Sierra.app/Contents/Resources/createinstallmedia: command not found