[kcox52692]

[A

Help! Trying to reinstall Mac OS X on a 2009 Mac Mini. A warning initially popped up stating that a newer version was installed than what I was trying to put in.

I just want to start from scratch. Each attempt gives me the same results.

[anon(9602380)]

You will need to first find out what version of OS X was originally installed on your Mini. Do you have the original disc that came with the Mini? The disc will contain the version of OS X that came with your device. If not you will need to find a copy of the disc. Many for sale very cheap.

[dcoke22]

An early 2009 Mac mini shipped with Mac OS X 10.5 (Leopard).
https://support.apple.com/kb/SP505?locale=en_US

I believe that Mac is old enough to not support Internet Recovery; you have to use physical media. Which, as it turns out, you can still buy from Apple if necessary.

https://discussions.apple.com/thread/6362900?start=0&tstart=0

[kcox52692]

I found out that I can make an appointment with the Genius Bar and they'll get the disc out and reinstall the os for free. What is the highest version of macOS it will support and how secure will it be?

[dcoke22]

macOS High Sierra requires a Mid 2010 or newer Mac mini.

macOS Sierra will work on a Late 2009 or newer Mac mini.

macOS El Capitan will work on an Early 2009 or newer Mac mini.

So, it depends on exactly which Mac mini you have.