Unable to access External Drives and Disk Utility after updating to macOS Sonoma.

Sonoma seems to have issues with Mac OS Extended (Journaled) formatted drives as well. I was using a high-speed 1-TB SSD as an external drive hosting the home folders (2023 Mac Mini M2, 16GB Ram, 256GB SSD). Worked perfectly until Sonoma. Sonoma seems to be designed to force people to use Mac-only software and hardware. Sucks for those of us with fixed storage on their systems. I've spent more than six hours troubleshooting with senior-level Mac support with no fix in sight. They've escalated to the engineering team. We'll see if they can do any better. Beginning to regret my Mac mini purchase.

I am running a Fortress secure external drive and having the same issue (since I upgraded the OS yesterday). If I try and open with the password (keypad on the drive casing) it doesn't unlock. If the drive is plugged in Disk Utility won't open. If I unplug the external drive Disc Utility opens instantly. If I then plug the external drive back in D/U doesn't see it.

However......I just plugged in a Western Digital (unprotected) external drive, formatted in ExFAT and it opened with no issue. It is allowing me to manipulate the files as normal?

I knew I should have waited...........

Same experience here. My 10TB LaCie d2 drive with exFAT failed to mount. I blamed myself for not disconnecting it properly...leading to corrupt file. Had to use EaseUS to get into the unmounted drive and copy the files (that software did a beautiful job).

Copied the files to my 14TB LaCie d2 drive...also exFAT...which was healthy and has always mounted. Then ran First Aid on the 14TB drive, and First Aid said that drive is failing and I must copy all those files over asap. This time I'm blaming exFAT. I'm going through the process of converting all my mechanical external drives to APFS.

Has Apple said anything about a big problem with exFAT?

emmyluty22 wrote:

You might want to do what I had to do. My exFAT drive failed to mount with Sonoma. A LaCie d2, 10 TB. Yikes. Even though the drive couldn't mount, I was able to get to the files using EaseUS data recovery software, $100 for a month.

Why didn't you just use the Windows computer for which you chose to format the drive ExFAT?

I had to go back to Ventura. External Hard drives keep getting this issue, and now i found that Mac crashes when i put a YouTube video in Picture in Picture in Safari and browse the web at the same time! I repeated this issue twice and i was like “no way I’m not having this” 

Since i use Macs i think I never had this bad experience with a new OS! Disappointed !!

I'm having the exact same issue ever since I updated to Sonama. It was so bad it fully corrupted two lacie hard drives, which cost me £320 to repair. I've spoken to apple, I've updated to the new 14.1.2, I have fully factory reset mac, and still causing me stress as it happens often, after ejecting fully. The next day I go to load hard drive, disk utility doesn't load and neither does my drive, have to use 2015 macbook to restore and luckily it does! So frustrated by this, but glad to see it's not just me. I formatted a new harddrive to mac only and that's of course working fine!

I've been testing a Kensington 960GB HyperX SSD connected with an Apricorn SATA to USB3 dongle and a USB-A to -C adaptor. I have tried everything mentioned here to corrupt the drive and I cannot.

The only thing I haven't done is pull it out while writing.

I've left it connected when I shut down.

I've just pulled it out of the Mac without ejecting.

I've written large and small files.

I open, edit and save the files.

I copy new files to the drive and edit them.

I play audio and video files from the drive. I haven't edited them as I don't normally do that. If people do that on them, what software do you use?

I am using a M2 Pro MacBook Pro running current versions of Sonoma.

I would love to file a bug report for this, but I cannot manage to replicate the problem. Does anyone have any other ideas of what I should be doing with the drive that is different than what I have listed?

Possibilities:

• Type of files
• Applications
• Drive utilities

I don't have any other SSDs to test.

Perhaps it is related to the controllers. Has anyone noted any particular make/model drives that are being corrupted?

The problem still persist for me.

Little walkaround working for me:

I noticed if i connect the Drive and wait for 10 or 20 minutes the drive become accessible.

if you want a correct working,The only solution is Rolling back to Ventura Hoping your sw maintain the compatibility.

Sonoma is the worst OS Apple did. Since i update my 2020 imac is Dramatically slow down. Have compatibility issues (my mac is used in music pruduction) and now, this great bug with exFAT drives.

Mac is not anymore adapt to professional use. Too issues if you work with customers with different platform and you had to share . Is unacceptable.

I hope Apple can solve it.

me pasa lo mismo. y la única solución a todos los problemas es volver a ventura. estuve 5 días sufriendo por la perdida de mis discos pero la verdad nunca fueron ellos. siempre fue el mal sistema. Mac debería hacerse responsable de todo esto.

I have resolved the issue with my last outstanding external drive that was resisting connection, an older model RocketStor RS6314A from HighPoint that needed a firmware update (done through my old MacBook) before I could run it with the newest driver available using my M1 MacBook Pro running Sonoma 14.2.1; and, everything seems to be working as expected now. Initially I was told this older model RAID external drive would have to be run on my old MacBook, or failing that, that I would need to upgrade to a newer model of external drive case; but after voicing my displeasure at that response, someone higher up in the company sent me an apology along with the instructions on how to update the firmware for the device and then load the newest driver available from their company.

totally. Spent 2 hours yesterday with Apple support and was useful. I just realized that can mount the disks through disk utility in safe mode but can't in normal one. Apple asked me to reset from factory settings my mac but don't wanna do it because it'll be a nightmare to get everything back.

Am I missing a step somewhere?

I think you are missing all of them: Create a bootable installer - Apple Support

Once the installer downloads, it will try to run, but you can't install an older version over the top of a newer. Quit the installer and follow the steps to create a bootable installer.

• Your post states in Item 2 "Sonoma may be finicky on your machine"

My machine is a low cost 2023 Macmini M2, 256g internal and 8g of RAM, that has a 2T SSD external drive plugged into usb-C/thunderbolt 4 port, formatted day 1 APFS, that worked perfect with Ventura, the origianl installed OS. Updating to Sonoma 14.2.1 put a quick end to this happy situation. After many hours of frustration over several days, I went full WOKE and "cancelled" Sonoma! Restored via a clean install Ventura then Time Machine restored back to wonderfully functional state of bliss I previously enjoyed. Sonoma is dead to me. BTW, I can't find any compelling reason for Sonoma to be worth the bother. To accept from the talking heads at Apple support the explanation that, as you state, "Sonoma may be finicky on your machine" makes my head feel like exploding. W. T. F.? Apple support? Give me a break! Shame on you all!

Update:

Talked to support...No solution, they think it is just the hard drive, although one is indeed faulty after everything that happened, it seems impossible since this happened to at least 5 different hard drives over the last days...so it must be the MacOS. Hope Apple will fix this asap.

They also suggest to just plug them in into a Windows Computer and fix it there...I've always loved my macbooks but this is a huuuuuuge dealbreaker!

Upon the addition of an external TB4 hub the external drives have become more stable. I am still in the process of reloading my audio samples libraries onto 2TB drive. I'll let everyone know what happens when I finish.