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Level 1

17 points

Problem with MacOS update 10.15.7 2020-001

Hello all,

I have an 2003 iMac, with 10.15.7 installed (Catalina) on an external SSD drive. The iMac boots on an external disk. Usually all security updates install correctly on the external SSD disk. For the last one, the installation seems ok, but the iMac reboots always on the internal HD. When I reboot on the external disk, the security updates seems not installed. I redo this operation multiple times, without success: the lastest update is proposed for installation, but when I do it, it does not install on the external disk...

What is happens ?

Thanks in advance

iMac 21.5″, macOS 10.13

Posted on Dec 15, 2020 4:42 AM

Best reply

CapsuleFab

Level 1

9 points

Posted on Dec 16, 2020 8:23 AM

Also had issues with this 10.15.7 2020-001 update. Here is what worked running an Imac 2013 from external SSD.

When starting the update, still on black screen, it had a brief reboot.
After that the Mac failed to load from SSD every time.
As my internal drive is a clone the Mac was only starting up with the internal disk, and not recognising the SSD as target disk.
Pressing option key wasn't working to select SSD disk.

What worked for me:

I unplugged everything connected to the Mac and plugged my SSD in a different USB (the closest to the edge)
Did a PRAM reset (once)
Switched on, loud startup sound and the Mac loaded my internal drive with the clone, then I shut down after loading
Switched on again and pressed option key (the SSD disk appeared)
After loading the SSD I noticed the update was still pending on Systems Pref
Shut down again
Switched on again to check it would load from SSD, and it did!
Performed the update with no problem after that

Hope this helps..

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Problem with MacOS update 10.15.7 2020-001

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