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How to install old macOS on old MacBooks?


macrumors regular
Original poster
May 15, 2014
I am using a MacBook Pro 13" 2018 running macOS Catalina as my main computer, recently bought a used MacBook Pro 15" early 2008 just to run some software for school. The 2008 MBP15 came with OS but weird thing happens to it: when I input in the dialog box the letters I just key in are not showing but it does make some error chime, but function keys are working normally, like brightness adjust. So I guess its Mac OS system is broken. Im replacing the original HD with an SSD anyway, so I don't care about its original system working or not.

I headed to Apple Online Store thinking to buy a Snow Leopard, which could be the best system for this MBP15 early 2008. Searched and found, pay $20, then it turned out to be a code emailed to me to be redeemed in Mac App Store, which I thought could have been a DVD.

Now the problem is, in macOS Catalina in my daily drive MBP, the old macOS won't show up. I did some research, just to find out that Catalina won't download any old macOS from Mac App store. So I turned to the archives in an external drive. There are 3 system install images in the external drive: macOS High Sierra, Sierra, and El Capitan. Only El Capitan is compatible with the MBP15 2008, so I tried to make usb install on 3 different USB keys using Terminal with code I found from Apple help page, on MBP13 2018, all of them were success of transferring install files from Application folder to keys, but all give me error after install on MBP15 2008, the installation went thru for about 20mins, then ended up saying "OS X could not be installed on your computer No package were eligible for install".

Seems like the install files were damaged in USB keys, but remember they were all successful when being made in Terminal on Catalina, and now all 3 USB keys with the install files have the same error. It just doesn't make any sense to me. Ok even if the Install macOS El Capitan file is really damaged, there's no way for me to download it again in Catalina. I don't have any other computer running old macOS to download old macOS. The only old macOS install image is "corrupted" (I believe it's NOT!!) I'm now in a dead loop !! I just want to install a system, any macOS, into the MBP15 early 2008! Why is it so hard? What's wrong with Apple?

(So I just bought the Snow Leopard DVD from eBay, but it won't arrive soon enough, so I still need to figure out how to do old macOS installation)
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