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User profile for user: wa2flq
wa2flq Author
User level: Level 1
10 points

Mac Mini Late 2012 cannot boot External Mojave Disk

I have two Late 2012 Mac Minis (6,1 and 6,2) running High Sierra. I am trying to boot a Western Digital external drive that has Mojave on it. The external drive boots successfully on an iMac Pro. While I can select the external drive to boot from "Startup Disk" or Option->"Startup Manager", its the internal mini disk (High Sierra) that gets booted. The Mini's are supposed to support Mojave. I reset the PRAM and SMC. Disk repair doesn't show any problems with the removable drive.


I disabled the internal drive on the 6,1 mini, but when I start it up I get the Question Mark Folder.


Is there something (EFI?) on the internal drive I need to update to get this to boot? Does the internal drive need to be running Mojave?

Mac mini, macOS 10.13

Posted on Jul 4, 2020 8:20 AM

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User profile for user: wa2flq
wa2flq Author
User level: Level 1
10 points

Posted on Jul 5, 2020 3:27 PM

I did manage to get the disk image to boot successfully.


The problem was with the size of the partition/container. I used the Disk Utility to resize the APFS partition to less than 2TB. Once I did that it booted cleanly when chosen from "Startup Manager". I am still using the 5TB disk, so it not the disk size per se, but the partition/container that has Mojave on it.


I guess it is still possible that an install of Mojave on the internal disk would have updated something and also solved this. I'll leave that exercise to a later time (or someone else ;-).




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User profile for user: wa2flq
wa2flq Author
User level: Level 1
10 points

Jul 5, 2020 3:27 PM in response to HWTech

I did manage to get the disk image to boot successfully.


The problem was with the size of the partition/container. I used the Disk Utility to resize the APFS partition to less than 2TB. Once I did that it booted cleanly when chosen from "Startup Manager". I am still using the 5TB disk, so it not the disk size per se, but the partition/container that has Mojave on it.


I guess it is still possible that an install of Mojave on the internal disk would have updated something and also solved this. I'll leave that exercise to a later time (or someone else ;-).




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User profile for user: HWTech
HWTech
User level: Level 9
60,578 points

Jul 4, 2020 11:14 AM in response to wa2flq

Have you ever installed Mojave on this computer (even to an external drive)? If not, then the system firmware is not new enough to boot Mojave. I've seen this happen with some our organization's laptops. Install Mojave or Catalina to an external drive after which you should be able to boot to the WD Mojave external drive.

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User profile for user: wa2flq
wa2flq Author
User level: Level 1
10 points

Jul 4, 2020 12:14 PM in response to HWTech

I was wondering if that was the case. I did check the support pages for Mini firmware updates. I did find a few, but turns out I had already installed them. Still, I guess the more recent OS installations may have a few embedded.


The other think I am researching is whether the disk I am using 5T is too large for firmware of the era. While the disk is recognized, perhaps the partition is too big..


Appreciate the reply!

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Mac Mini Late 2012 cannot boot External Mojave Disk

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