Security Update 2020-001 10.15.7 destroys Mac mini Late 2012?

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Level 1

14 points

Security Update 2020-001 10.15.7 destroys Mac mini Late 2012?

So... when I installed this on my Late 2012 Mac mini, the system would fail during boot, stuck at the white apple, no bar build beneath, can leave it for a day, stays stuck (I think this is a fault during loading the boot ROM, which is modified in this update?). So, I booted from another Catalina disk, used Disk Utility to erase and reformat the updated disk (a Samsung USB external SSD, see system info below), boot in Recovery mode and install a fresh Catalina on it, nothing else. Then I tried installing the update when prompted automatically by Software Update. Same problem. Looking around, it looks like this might be a problem related to the new Boot ROM version and maybe how it effects the ability to boot from an external USB... or something else.

I also note that, if I do a hard reboot and go to Recovery Mode and tried to Reinstall, but got an error that this could not be done, as there was no network connection. This reminds me of issues that Big Sur Beta had with Late 2012 minis, which is likely why they are not supported in Big Sur, where wifi was sketchy and other difficulties. I wonder if some errant code incompatible with my system made it into the Boot ROM update?

For now, I've reinstalled Catalina again, turned off automatic updates and updated Safara, but have not applied Security Update 2020-001 10.15.7, but, I would really like to turn automatic updates back on... someday. Please advise if any ways to fix this or any plans for an update with regression testing for mini 2012?

If necessary for debugging, I can recreate this one more time, let it hang for a while, then restart and boot from my backup HDD, then grab any log files from the external SDD that would be helpful.

Thanks, Bee

System Info

Mac mini, macOS 10.15

Posted on Jan 20, 2021 12:30 PM

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Answer 1

bee61 Author

Level 1

14 points

Jan 23, 2021 4:55 PM in response to a brody

Well, I found a fix. Running the Catalina installer that was in ../Recovery seemed to run correctly, but resulted in a disk with no OS X installation at all, just a few files copied, so I booted in Recovery mode and used the latest time machine backup. What's weird is that now my mac mini is booting from the SSD again AND I'm now running 10.15.7 successfully. OK, just weird, but I'll take it!

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Answer 2

a brody

Level 10

85,366 points

Jan 20, 2021 12:38 PM in response to bee61

At least you had a backup.

Yes it probably is some Boot ROM issue. The progress bar stuck issue often indicates something in the Boot ROM did not compatible upgrading correctly.

Your free disk space does not lead us to believe it is a problem there.

The one other problem, machines those old often start to have failing hard drives leading to random fluctuations in reliability.

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Answer 3

bee61 Author

Level 1

14 points

Jan 21, 2021 10:53 AM in response to a brody

Frustrating stuff.

The bad: So, I think my SSD needs a firmware update from Samsung. The latest update from them did not fix it, so maybe they need to build a new one, I will ask. If not, I may just see if I can replace the internal drive with a SATA SSD (though I could imagine that booting to install Catalina on that could be... challenging).

The ugly: Argh. Since I ran migration assistant, all my Time Machine backups prior to that time are ... gone? Odd, as the disk is still quite full, but only appears to have backups now going back to when I ran Migration Assistant.

The good: BUT (and it's a big but!)..., I found a Recovery directory in the oldest backup on the drive and it had a BaseSystem.dmg from late 2020. I unpacked it and installed it on the SSD. I'll let you know if that allows me to reboot (it still may not, as I am unsure it would overwrite the boot rom with an older version. Still, if the problem is EFI, it might fix it. We'll see...

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