Can I install Sierra 10.12 on a 2017 MBP ??


macrumors newbie
Original poster
Nov 14, 2019
Hi Everyone! My slow old 2011 MBP with Sierra 10.12 finally needs replacing. I've bought a used 2017 MBP that comes with High Sierra 10.13 natively installed. I have a couple of obscure yet important 32-bit applications that won't run past Sierra, but I'd REALLY like to keep using them (the developers have no intention of updating them to 64-bit). I not fussed about having a later OS, I'm quite happy with Sierra. Can I 'downgrade' this 2017 MBP down to 10.12 Sierra? I read somewhere that this is not possible on a later MBP that shipped with a later OS, not possible to go backwards like this. Any advice would be GREATLY appreciated!
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macrumors regular
Aug 15, 2004
macOS Sierra - Technical Specifications

I'd cloned both your laptops and put the clones away on an external HD if you can, just in case, with CarbonCopyCloner and select compressed the archive method. After putting both machines on a network where they can see each other, then wipe the 2017 machine and install a clean copy Sierra from a Thumb Drive or External HD. Then in the part of the install of Sierra where it asks if you want to Migrate from another source, select the 2011 and copy over your "old" machine to the newer one. Or if you have Time Machine backup, I think you can select one those.

I wiped my newer laptop and cloned my Mac Pro Sierra partition on to the laptop, after having Mōjāv on it. Now I have two identical machines of sorts. Now I have many partitions that have many other OSs on them in the Mac Pro and a couple of the laptop so I have done this a lot!! If you drive is large enough, I'd partition it and make you some safe storage space. OR if it's really big do a couple partitions and make one for storage and another for Time Machine.

Hope this helps . . .
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macrumors 68030
Jan 19, 2015
Oregon, USA
The 2017 MBPs originally shipped with 10.12.5. As long as you install 10.12 6 (the final version) then it should work. Just keep in mind that the Apple Sierra certificate for the Sierra installer expired Oct 24, 2019. If your copy of Sierra was before that time then it will not run.


macrumors newbie
Nov 20, 2019