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

What I ended up doing: used EaseUS software ($100) on the drive that wouldn’t mount. It allowed me to go in and copy over the files. Just copying a recovered folder wasn’t enough, I had to dig deep and copy individual files (especially needed my video clips). I’ve ordered a new drive and will format that as APFS then move the files there. Then plan to reformat the problem drive, this time using APFS. Expensive buying a lot more drives so I can have 3 copies of essential video projects…original and 2 backups, each on separate drives.

I had some issues with one of the latter Ventura updates using MacOS Extended on external drives I use for Time Machine and Media storage. Support eventually recommended reformatting both drives to APFS and all has been well since, including the Sonoma update which snow running as it should. Unless you need exFAT, you might try APFS.

Similar issue. Reinstalling Ventura seems to have at least returned me to a workable state. I am considering reformatting my external to AFPS. From what I have gleaned from others’ experiences, Sonoma only plays well with AFPS.

Yes a good tip I have read about if you're in exFAT the Sonoma won't mount the drive: find a Windows PC, use their repair option as people say that fixes things, but also I would then copy the files off to a new external drive formatted in APFS, and then you can for sure use that drive on Sonoma. APFS.

I just wanted to follow up on my previous reply about having slowness problems.

I use an OWC Thunderbay Mini external drive exclosure (not set up as RAID) for SSD drives. I talked to OWC to be sure there are no known issues on their end. There are not. I had no problems before upgrading to Sonoma.

Because someone else in this thread mentioned that the way the drives are formatted, including Mac OS Journaled, could be causing the issue, I decided to reformat the drives. This required moving stuff around and making backups, but I took the time and did it.

My drives had been formatted for Mac OS Journaled.

I erased and reformatted them to APFS.

My problem is gone. It is a night-and-day difference.

Just to reiterate, I had NO ISSUES before upgrading to Sonoma. It wasn't a drive going bad because it happened across all external drives. The problem was slowness and lagging when trying to read the contents of any of the drives. All were formatted to Mac OS Journaled. Now formatted as APFS the problem seems to have gone away.

Have you tried plugging your old drives into a Windows PC?

Sonoma didn't read mine properly, but the WinBox didn't have an issue.

Ended up running freesync to compare the two drives with windows (its the same content, the 60TB was/is filling up, so I got the 88TB for the extra room) when I determined the 88TB and 60TB were the same, I killed the 88TB, formatted it as APFS and copied the 60TB to the 88TB, and then I used DirEqual to check that the 88TB had the same as the 60TB, formatted the 60TB and copied the 88TB to the 60TB so I'm back to both drives being the same, and both being APFS, then I purchased a copy of Paragons' APFS+ for Windows in case I need to use one of the drives in a windows environment.

Thanks Uncle Tim...

Hello,

Just found a solution; if you have exfat external hdd and you're trying to connect it with an usb type a to type c adapter, it does not work.

I just bought new usb type c to micro b cable and connected it directly to mac, it works like magic! :)

I had to use data recovery software EaseUS. Cost about $100 for one month use. That lets you look inside the unmounted drive and then you can copy files to another drive. I think issue is exFAT formatting and I've changed everything to APFS.

This solution worked for me.

Firstly, I have a Sandisk SSD USB-C (formatted in NTFS). It was working fine in Sonoma until today where it wouldn't mount at all, and Disk Utility wouldn't even load any of my Disks/Volumes while the drive was plugged in. I'm not sure what's causing the problem but Apple support wasn't much help.

While attempting to access the drive in Recovery Mode on my M1 MacBook Air I was unable to even load it via Disk Utility. Disk Utility just gave me a loading curser animation.

So... I had to connect the drive via a USB-C to USB-A dongle to my older Intel MacBook Pro (which only has USB-A), run disk repair via Terminal, and UNMOUNT, and EJECT, the drive safely via terminal. Then it mounted just fine back on my M1 MacBook Air in Sonoma 14.2.1. (The repair told me that my disk was fine, btw.)

You can find instructions on how to run a repair on a volume via Terminal online. Here's an example:

https://gist.github.com/bzerangue/dca8fc2d63309ba2bd9f

You then have to unmount the drive using "diskutil unmountDisk /nameofdisk"

Then, also eject the disk using "diskutil eject" command. (Again, instructions for this are easy to find online.)

I think the problem is that the ExFat and NTFS disks/volumes aren't ejecting properly in Sonoma. So, a good solution would be to actually use the terminal to unmount and eject the volumes/disks manually to be safe.

I have a pretty much state of the art 2023 Mac Mini M2 8G ram, 256 internal, and a 2T external SSD FORMATTED in APFS since day 1. The computer came with Ventura installed and the SSD worked perfect! Then I recently migrated to Sonoma 14.2.1 and the external ssd drive disappeared after rebooting, never to be seen again by Sonoma.

I tried all the tricks and still no external ssd to be found. 

It is an outrage that the recent update Sonoma 14.3 does not correct this critical flaw!

Out of frustration, I concluded that Sonoma sucks and I restored Ventura as follows:

On a Mac with Apple silicon your computer must be connected to the internet. If you’re reinstalling on a Mac laptop, plug in the power adapter.

1. Shut Down your Mac, press and hold the power button until “Loading startup options” appears, select Options, click Continue, then use Disk Utility in the Recovery Window to initialize your drive APFS, which wipes it clean.
2. Then, In the Recovery app window, select Reinstall for your macOS release, click Continue, then follow the onscreen instructions. 

After I reinstalled Ventura, I restored the most recent Time Machine backup, which was only 2 days old. Being very grateful that all my precious data had not been chewed up and destroyed by Sonoma as some have reported happened to their external drives data. Did I mention that my Time Machine is on the external SSD?

I’m happy to be back with Ventura. For me, there is absolutely nothing compelling about Sonoma that warrants having to put up with any hassles with it. 

[Edited by Moderator]

Okay I just updated from Sonoma 14.2.1 to 14.3.1 and now suddenly the drive is working again.

I checked both hard drives with "First Help" from the old Mac and when I opened them again with Sonoma they worked perfectly.

Hello!

For me in solving this issue on a MacBookPro M1 was:

System settings > Privacy & Security > Scroll to "Security"

"Allow Accessories to connect" to "always"

That's all

Best regards and good luck :-)

Ingo

Was your drive formatted in exFAT. Mine was and wouldn’t mount. Had to use EaseUS data recovery software to get into drive and copy files to new drive I formatted in APFS.