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Problems installing 10.15.3

I have a late 2015 iMac running 10.15.2, but every time I try to update to 10.15.3 it crashes, and displays the screen below. If I choose to restart it asks me to select the startup disk, then restarts fine.


I have plenty of space on my hard drive (approx 1 TB), I’ve tried rebooting in safe mode, and I’ve run disk utilities and found no problems.


I’ve also tried using the combo updater, which resulted in the same problem, and I’ve tried reinstalling from the recovery disk but it crashed.


I’m completely stumped about what to do. Any suggestions gratefully received!


iMac 27", macOS 10.15

Posted on Feb 7, 2020 8:10 PM

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Question marked as Top-ranking reply

Posted on Feb 8, 2020 4:13 PM

First make sure to backup your system immediately while you can still easily access the system so you don't lose any data.


You can try running the Apple Diagnostics.


If you want to check the health of the hard drive before going further (recommended), then run DriveDX and post the report(s) for the hard drive (and SSD if a Fusion Drive setup) here using the "Additional Text" icon which looks like a piece of paper.


Once everything is backed up, I would suggest booting into Internet Recovery Mode using Command + Option + R to launch the online Catalina installer. You can try installing Catalina over top of itself in order to retain your data and settings, but if this does not work, then I would suggest performing a clean install/restore by erasing the whole physical drive using Disk Utility. To see the physical drive click on "View" within Disk Utility and select "Show All Devices" so that the physical drive is shown in the left pane of Disk Utility. Select the physical drive (Apple SSD...., or Apple HDD....., or Fusion Drive....) and erase it as GUID partition and APFS (top option). Then quit Disk Utility and select either "Reinstall macOS" or "Restore from a Time Machine Backup".

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Question marked as Top-ranking reply

Feb 8, 2020 4:13 PM in response to jamesbradley

First make sure to backup your system immediately while you can still easily access the system so you don't lose any data.


You can try running the Apple Diagnostics.


If you want to check the health of the hard drive before going further (recommended), then run DriveDX and post the report(s) for the hard drive (and SSD if a Fusion Drive setup) here using the "Additional Text" icon which looks like a piece of paper.


Once everything is backed up, I would suggest booting into Internet Recovery Mode using Command + Option + R to launch the online Catalina installer. You can try installing Catalina over top of itself in order to retain your data and settings, but if this does not work, then I would suggest performing a clean install/restore by erasing the whole physical drive using Disk Utility. To see the physical drive click on "View" within Disk Utility and select "Show All Devices" so that the physical drive is shown in the left pane of Disk Utility. Select the physical drive (Apple SSD...., or Apple HDD....., or Fusion Drive....) and erase it as GUID partition and APFS (top option). Then quit Disk Utility and select either "Reinstall macOS" or "Restore from a Time Machine Backup".

Feb 8, 2020 9:52 PM in response to HWTech

Thank you. I did as you suggest and wiped the disk and reinstalled from scratch. Once I did 10.15.3 installed without a problem.


One thing I did notice while I was poking around trying to isolate the problem was that FIleVault seemed to be playing up, so it was impossible to turn off either through System Prefs or Terminal. I wonder whether that had something to do with the installation problems.


Thanks again.

Problems installing 10.15.3

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