Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

User profile for user: John Baughman
John Baughman Author
User level: Level 1
50 points

Mac OS update repeatedly fails, leaving start up drive un-bootable

I have an iMac currently running Big Sur. My startup drive is my internal SSD. I have made a bootable backup drive with an external SSD ( using Carbon Copy Cloner). Both the main drive and the backup drive boot fine and operate normally. HOWEVER--


if I try to update the MacOS on the internal SSD the update fails and renders the drive in an un-bootable state. For example, updating from 11.4 to 11.5, whether through "About This Mac/Software Update" or while in recovery mode, results in an error message saying basically "Software Update Failed". The data partition of the drive is intact but the other partition isn't shown in Disk Utility.


On the other hand, if I do a software update on the external SSD exact clone, the update proceeds without difficulty. The only way I can update the internal SSD is to erase it and clone the external SSD (with the newest OS) to the internal SSD.


Any help or suggestions will be greatly appreciated.

John

Posted on Jul 23, 2021 7:44 AM

Reply

Similar questions

5 replies
Sort By: 
User profile for user: HWTech
HWTech
User level: Level 9
63,338 points

Jul 23, 2021 9:34 PM in response to John Baughman

Try running DriveDx to check the health of the internal SSD. Post the report here using the "Additional Text" icon which looks like a piece of paper.


What is the exact model of your Mac? You can get this information by clicking the Apple menu and selecting "About This Mac".


Try running Disk Utility First Aid on the hidden Container on the internal SSD. Within Disk Utility click on "View" and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. Even if First Aid shows everything is "Ok" click "Show Details" and manually scroll back through the report looking for any unfixed errors. If there are any unfixed errors listed, then you will need to erase the whole physical SSD and restore from a backup or clone.


It also never hurts to run the Apple Diagnostics to see if any hardware issues are detected.



Reply
User profile for user: John Baughman
John Baughman Author
User level: Level 1
50 points

Jul 26, 2021 12:12 PM in response to HWTech

Thanks for responding to my request for help. I have done several tests. As you suggested I ran Apple Diagnostics which showed no problems or errors. I ran DriveDx and it also reported no problems. I have inclosed the report that was generated.


I then ran TechTool Pro on the drive itself and found no problems. HOWEVER, in running TTP I discovered that the RAM check test failed ( "Stuck Address Failed"). Next I ran Rember to see if it confirmed a RAM problem. It also showed RAM test failure, reporting the same problem, "Stuck Address". "FAILURE! Data mismatch at local address 0x00000009643a60b8. Actual Data: 0xffff40f69bc59f47 I'm not sure how to interpret this precisely, but I'm sure it points to a problem with a RAM stick. Not sure where to proceed from here. And I'm not completely certain that this RAM problem is causing my original problem mentioned in my original post. Any ideas would be greatly appreciated.


My Mac is iMac (Retina 5K, 27-inch, 2020); processor: 3.6 GHz 10-Core Intel Core i9; Memory: 64 GB 2667 MHz DDR4

Reply
User profile for user: John Baughman
John Baughman Author
User level: Level 1
50 points

Jul 26, 2021 6:08 PM in response to John Baughman

Yep! That was the problem. One 16GB stick of RAM was producing the "Stuck Address" failure message. After trial and error I was able to identify the bad memory module. It is an OWC RAM module and it has a replacement guarantee. I'm sending it in for a replacement. Mac OS 11.5.1 update was released today. I held my breath and did the update. It worked flawlessly this time. I love the Rember app! Very nice for checking RAM.

Reply
User profile for user: HWTech
HWTech
User level: Level 9
63,338 points

Jul 26, 2021 8:35 PM in response to John Baughman

Good job on tracking down the bad memory module. Keep in mind "Lifetime" warranties do not mean you can get a replacement module for free until the end of time. You will only get a free replacement module as long as that module is still being made and is still in stock. OWC definitely has great tech support & warranty service (as does Crucial).


If you continue to have issues you may need to perform a clean install of macOS and just restore your user account(s) from a backup. Or if you know when the issue first began you could restore the system from a backup/clone from before the issue began. Sometimes a bad memory module may have corrupted some of the software (macOS system files, apps, data, or even file system). Just something to keep in mind.


FYI, I am personally not a fan of TTP. Our organization used it years ago (PPC era mostly - and I checked it out more recently as well) and was never impressed by it since other apps at the time did better jobs (even if separate apps were needed for the same functionality). I was even more disappointed by TTP when I tried it a few years ago (out of curiosity). If you want to monitor the health of a drive, then DriveDx tends to be a bit better and nicer. If you are using APFS, then the file system repair utility for TTP is not an advantage since Apple has not released the necessary documentation for APFS file system. If you want to check the memory, then Rember is an option as is MemTest86 (a bit difficult to use on a USB-C Mac though). If you want to stress test the system, then "mprime" (aka Prime95) is the king when using its "Torture Test" mode.

Reply

Mac OS update repeatedly fails, leaving start up drive un-bootable

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.
Learn more Sign up