As such you should clone the drive so you can go back to your last backup.
Nod to https://www.google.com/search?q=superduper+disk+clone
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I am running the latest version of Sierra and I wish to make a bootable Yosemite or El Capitan install drive for my daughter who is running Lion. She doesn't want to upgrade to Sierra because one of her key apps won't run on it.
Firstly, is it possible to create a lower-level OS bootable drive on Sierra 10.12.5?
If it is, I have a further problem. I follow the standard instructions, all of which involve the Terminal command:
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
or sometimes that with " --nointeraction" tagged on the end.
In both cases, I get the message, "/Applications/Install OS X El Capitan.app does not appear to be a valid OS installer application.", even though I have previously made a bootable disk from that file.
Is there something else I can do?
Discussion is locked
... because my daughter's Mac is on Lion and she wants to upgrade to either Yosemite or El Capitan - she wants to go forward
I'm puzzled as to why I was able to make one before but can't now. Is there no other way to make a bootable drive?
Alternatively, is there a way to download a Yosemite installer?