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

I have this issue also. Home directories on external drives formatted as HFS+ journaled. Slow, lots of spinning beach balls. Calendar alerts running Automator cannot be scheduled. Mdworker has been running for days. Submitted bug report with debug information while Calendar and Preview were spinning but they never answer.

Apple doesn’t call it bug reporting any longer. It’s now called Feedback. Here is my Feedback number FB13246120 if any one from Apple actually reads this.

Only solution that I know of is to go back to Ventura.

I agree it is not ok but I couldn’t wait for another update hoping it would fix the issue. Updated the external raid volumes to APFS and at least now apps are working again. So it’s definitely an HFS+ on external disk problem. Bummer. Apple rushed this out the door.

Thanks for your information. A big problem here. For me it was exFAT drive not mounting in Sonoma. I had to use EaseUS software ($100 for one month's use) then could get into the drive and copy over files. Apple needs to take care of these problems or at least acknowledge and warn people.

Best of luck.

I had to downgrade from Soonoma to Montrey surprisingly only thing those OS bring is the new apple silicone features.

if your looking to downgrade just copy your home folder to a external drive from time machine backup. and copy it to the home folder of your user in any mac os. should sync up everything.

I run a couple of Apricorn 2TB secure HD's. They have to be formatted with exFAT as I use them at home (MAC) and work (Windows). I have the same issues as described in this forum and it is about time Apple rectified it. My alternative is just to scrap MAC completely.

I have noticed that small thumb drives have no issue switching between platforms. To get the Apricorns to work I have to do a disc repair in Windows (nothing is 'repaired'). Then it will open on my MacBook. If I then shut it down, even correctly, it won't re-open and Disc Utility won't open with it plugged in and doesn't see it if I open D/U and then plug in the Apricorn. I need to take it back to the Windows computer at work.........so I need to make sure I don't need to access the drive twice while at home.

Come on Apple, you should be better then this.....

Henry, has Apple stepped up and solved your problem? Just wondering? I have a 2023 Mac Mini M2 came with Ventura and an 2T external SSD formatted APFS day 1. Blazing fast, faultless performance, until Sonoma came to town. I rebooted and my 2T external was no where to be found. Tried it all, nothing worked! Used repair console to clean install Ventura 13.6.3, rebooted, lo and behold, my lost but now found 2T SSD had appeared with my Time Machine backups, with which I restored all my personal stuff.

Same here,

Yesterday, my 8tb seagate worked just fine, now it doesn't show up and disk utility is stuck on "loading disks". I did eject the hard drive properly and everything, now it just seems to happen randomly. I have already lost a 2tb Lacie last week, hopefully I will be able to repair it with an older Mac. It is a flippin' shame that Apple doesn't do anything about it, it really looks like as it is a Sonoma issue...

My usual work around is to plug the ExFat hard drives into a Windows Laptop and repair it there. But I am still scared to damage my hard drives or loose data...

A solution that worked for me:

Connect the ssd using usb-c to my Android phone, after a few secs just unplug it and connect it to the mac and problem solve, not the best, but at least this allows you to keep working and just loose a few secs every time

I'm not techy so apologies if not relayed properly but this has been my experience. I had a 5TB Lacie drive, after the upgrade to Sonoma, the drive will not mount. Spent 7 hours on the phone with an Apple "engineer". Changed security settings, modified different items on the computer trying to problem solve. Nothing. Then tried my old computers - no longer recognizable. The engineer could not figure it out. Told me I need to reformat my drive to work with Sonoma and try data recovery for my hard drive, probably will come with a cost. I gave up. Bought a new 8TB LaCie drive off the Apple site. (By the way I have the new M3 MacBook Pro. I waited to get the M3 because my iMac and MacBook are both no longer supported even though they worked perfect, they are circa 2013.)

New LaCie 8TB drive works for about two weeks. Then stops being recognized - after of course I had moved all my data to the drive. Spent another full day on the phone with Apple Engineers. No solution. They are escalating to Senior Engineers and will "get back to me". Expect 1-2 weeks. I sent them this thread.

Then I called LaCie. They have agreed to a "complementary" recovery on the 8TB drive I bought less than three weeks ago, but my other drive which is no longer under warranty, the original 5TB Lacie Rugged - they basically told me too bad. The 8TB recovery - likely will take 30 days.

I also have two WD externals and they seem to currently be working fine, but my LaCie d2 Professional (8TB) was also working fine for several weeks before it stopped being recognized.

FYI...M3 you cannot go backwards with the OS. No longer an option. If you can avoid updating to Sonoma - I'd recommend putting it off.

I was told by Seagate / LaCie this also happened with Ventura. Regardless - I'd be VERY careful with any external drives with significant data on a computer running Sonoma until they is resolved. Currently - NOT RESOLVED by Apple or Seagate / LaCie. As of right now, I would NOT connect it to your computer with Sonoma until this is fixed.

Do not throw your external hard drives out, your information is probably still there. I plugged in my 11yr old mac and my external hard drive still works there, but won't work on my new mac, it's definitely the Sonoma OS. Total Tech told me that Apple is working on a fix, but there was none as of last week.

I have an Mac Studio with Sonoma and my SanDisk Professional Thunderbolt 2TB SSD for video production that was formated exFAT and had all the same issues mentioned here. (Was just glad I had a PC with thunderbolt to repair the drive and get my data off).

Since I really only needed this drive on my Mac, I then formated it APFS. Now it will lock up the finder if it is connected for more then 20 min. Once this happens, using force quit to relaunch the finder only shuts the finder down without relaunching it, making it hang on shutdown or restart. So now the only fix has been to hard power down holding the power button. Once it reboots, it all works again. I can now use the drive, but I can only use it to transfer files quick and eject it before it freezes my finder once again.

This seems like a bigger issue then just exFAT, I have been having all kinds of quirky issues with any wired peripherals since Sonoma (like a Blackmagic Ultra Studio only being recognized 50% of time when connected via thunderbolt USB-C).

The thing that bothers me the most is that until Sonoma, if there were big issues like this (and this is BIG) that hinder businesses from working with Apple products, Apple would be on top of it and have a fix fairly quickly. But when I talk with Apple, it is like they have no idea there are any issues. I mean, if we are all having this problem, it would make sense that the employees at Apple (at least some of them) must be having these issues also. It is just the lack of acknowledgment that is odd.

Might consider this until Apple fixes Sonoma:

https://www.sweetwater.com/sweetcare/articles/macos-sonoma-operating-system-downgrade-guide/

Exact same issue with my exfat. Downgraded the OS and we’re back up and running hopefully this gets resolved soon.

There's a fix currently in progress. It will be available in the form of an upcoming 14.4.1 update very soon.

What helped for me is connecting the drive to a usb charging device.