High Sierra - Catalina dual boot possible?

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High Sierra - Catalina dual boot possible?

I have a 15" mid-2012 i7 MacBookPro running High Sierra 10.13.16. It runs perfectly fine and I still use it because I have some 32-bit apps that I want to keep using.

I would like to install Catalina on a bootable external drive. The MBP is qualified for Catalina and I know how to install it.

My question is ... since installing Catalina includes certain firmware updates, once I install Catalina on the external drive, will I still be able to boot High Sierra from the internal drive ... ending up with a dual-boot system?

Earlier Mac models

Posted on Nov 17, 2023 2:06 PM

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Answer 1

Nov 17, 2023 2:41 PM in response to MartinR

Yes, you can still boot the older High Sierra OS even though the machine has any firmware updates required for Catalina.

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Answer 2

Nov 18, 2023 7:32 PM in response to MartinR

Keep in mind that you will probably want to keep the High Sierra and Catalina versions of your iTunes and Photos Libraries separate.

Catalina may decide to do one-way "upgrades" on these libraries – especially on the iTunes Library, considering that Catalina replaces iTunes with separate apps. If all you have are the new versions of the libraries, you might have trouble taking those back to High Sierra.

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