User profile for user: simonp_au
simonp_au Author
User level: Level 1
30 points

SDErrorDomain error 108 when trying to boot from external SSD, Mac Mini M2

What I have done:


"

Change your Mac startup disk - Apple Support


"Change your startup disk for every startup

  1. On your Mac, choose Apple menu 
  2.  > System Preferences, then click Startup Disk 
  3. .
  4. If the lock at the bottom left is locked 
  5. , click it to unlock the preference pane.
  6. Click the icon of the disk you want to use, then click Restart.

WARNING: When selecting a network startup volume, make sure you select a network startup volume and not a network install image. Choosing a network install image reinstalls your system software and may erase the contents of your disk. A standard network volume icon appears as a globe with a folder. A network install icon appears as a globe with a downward-pointing green arrow."



If you are seeing errors you might consider checking the disk for errors in Disk Utility.


How to repair a Mac disk with Disk Utility - Apple Support


Also, after backing up any personal files, you could consider formatting the disk and reinstalling macOS on it.


Erase and reformat a storage device in Disk Utility on Mac - Apple Support"


My issue:



I have a brand new 2023 Mac Mini M2 8GB 256GB. I am attempting to use an external SSD (NVMe in an enclosure) as the main drive. 


I reformatted the external SSD to AFPS GUID and named it Ext Macintosh HD. I then downloaded the latest Sonoma today from the Mac App Store. I installed Sonoma to the external drive successfully, the Mac Mini then rebooted and it booted back up into the internal drive. I tried setting the Startup Disk to the External SSD in System Settings and then attempted to reboot and I received this message:


An error occurred while setting “Ext Macintosh HD” as the startup disk: The operation couldn’t be completed. (SDErrorDomain error 108.)


I have attempted this a few times with the same result each time.


Does anyone have any experience with this?


I read that the booting into recovery (holding down the power on button on the back of the Mac Mini) and then allowing the Mac to boot from an external drive is possible but I followed the instructions from a website and there was no setting that allowed that, just a reduction in security settings.

Posted on Dec 7, 2023 02:00 AM

Reply
Question marked as Top-ranking reply
User profile for user: woodmeister50
woodmeister50
User level: Level 7
20,859 points

Posted on Dec 7, 2023 05:08 AM

What brand and model SSD?

Is it a DIY enclosure/NVME? If so which enclosure and which SSD?


In the past there was an issue with Apple Silicon Macs being very fussy about the drive used for external booting. It seemed that Thunderbolt3 was generally the most reliable and any of the different flavors and makes of USB "type" drives (not going to get into the issue of all the different versions of USB these days). Note: USB-C is just a connector specification and to some extent has nothing to do with what travels over that connection.


Also note, if using a DIY enclosure/SSD, even Thunderbolt, can be very pick about the combination of enclosure and drive in terms of booting and even in terms of just plain functioning.


The error you are getting could be due to the above.


The other problem could be on what you did when you created the install in terms of ownership and how you actually did the install. I had the best success by entering recovery, erasing the external drive from Disk Utility, and installing MacOS from recovery to the external drive. Also, generally successful, was creating a USB installer, booting to it and use it to erase and then install macOS.

View in context

Similar questions

3 replies
Question marked as Top-ranking reply
User profile for user: woodmeister50
woodmeister50
User level: Level 7
20,859 points

Dec 7, 2023 05:08 AM in response to simonp_au

What brand and model SSD?

Is it a DIY enclosure/NVME? If so which enclosure and which SSD?


In the past there was an issue with Apple Silicon Macs being very fussy about the drive used for external booting. It seemed that Thunderbolt3 was generally the most reliable and any of the different flavors and makes of USB "type" drives (not going to get into the issue of all the different versions of USB these days). Note: USB-C is just a connector specification and to some extent has nothing to do with what travels over that connection.


Also note, if using a DIY enclosure/SSD, even Thunderbolt, can be very pick about the combination of enclosure and drive in terms of booting and even in terms of just plain functioning.


The error you are getting could be due to the above.


The other problem could be on what you did when you created the install in terms of ownership and how you actually did the install. I had the best success by entering recovery, erasing the external drive from Disk Utility, and installing MacOS from recovery to the external drive. Also, generally successful, was creating a USB installer, booting to it and use it to erase and then install macOS.

Reply

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

SDErrorDomain error 108 when trying to boot from external SSD, Mac Mini M2

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