Install older system on external disk

Question

Install older system on external disk

Hi,

On a MacbookPro the latest Catalina is running. I like to have parallel on an external disk the former Mojave installed as alternate boot to use it for some 32 bit Applications.

I downloaded the installer App new but Catalina does not open the Mojave installer App.

It is too old.

I'm looking for some work around.

I have a Time Machine backup of Mojave from before I installed Catalina.

Thanks for any help

G.

MacBook Pro, OS X 10.10

Posted on Dec 4, 2020 3:06 AM

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Answer 1

Dec 4, 2020 6:17 AM in response to dialabrain

Thank you very much. I did that, sInce I had such an USB Installer. I got stuck when the external device, I tried a new APFS partition, and a drive with Mac OS Extended ..., were not accepted as install device. They had no GUID partition. I could not figure out how to make with Disk Utility that partition.

G

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Answer 2

Dec 4, 2020 7:57 AM in response to dialabrain

After downloading Mojave again, this time on the latest Big Sur system, and creating again USB Installer I succeeded making a Mojave system on the APFS drive partition (part of a large WD drive). That worked as expected and I have not understood why it failed on y other Catalina MacBook Pro. I tried the same WD drive but with an older Installer (Catalina). I see a warning that the drive uses feature the Mojave system does not support.

Many thanks dialabrain I appreciate your input.

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Answer 3

dialabrain

Level 10

126,581 points

Dec 4, 2020 6:42 AM in response to Gerfried Kumbartzki

Are you trying to install Mojave on a partitioned drive or are you going to use the entire drive for Mojave? If partitioned, what's on the other partition and how is the drive formatted?

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