External hard drives don't mount under sonoma

same issue here, first I was worried my external are broken, spent $$ for a new SSD external drive and same issu. However if I plub into a microsoft PC it works fine. under Properties and tools I select repair what is a scan. I can use it for few hours on my MAC till I have the same issue over again extremly frustrating

Smowtion, I don't remember much more detail than I described, and I'm afraid I don't remember the exact sequence of steps and clicks. Naturally I first restarted the computer a couple times to see if that worked, but it didn't solve the problem.

Then I opened Disk Utility where I could see my Time Machine drive as an unmounted external device. It's not a SSD but a USB spinning hard drive, formatted with GUID Partition Map, and APFS (Case-sensitive, Encrypted).

I tried a few times to mount it by clicking on the Mount command on the top menu bar of the Disk Utility window. Eventually it asked me for permission to use Keychain. I think I clicked that once and it still didn't mount the volume, but the next time I clicked on the option to let it continue to use Keychain (sorry, I don't remember the exact wording) and it mounted, and since then it has worked, and then when I plugged in my USB flash drive (also APFS and encrypted), that mounted by itself although it wouldn't mount before.

Sorry I can't be more exact. I was just kind of trying whatever I could think of until it worked. That's as close as I can reconstruct it. Good luck!

This sorta worked for me, but It dropped the drive again after another restart. I then reformatted as an unencrypted drive (using for time machine backup) and started a new Time machine from scratch with the unencrypted formatting.

My encrypted SD is 1GB so not a 3TB+ problem. I created a new SD (16GB) AFS drive with encryption this afternoon to see if maybe an SD created from the ground up with 14.1.2 would work any better but still no prompting for the password and still able to mount it only with the disk utility.

I also did the 14.2 OS upgrade this afternoon and the issues are still there. So no fix. I guess I will try to Monday to do a chat with support and point them to this whole discussion to see if they would admit they are aware of the issues we are discussing here. Thanks.

I should have also added that if I shutdown the laptop and then start from the ground up the disk will prompt for the password and mount properly but if you eject the disk and then try to remount it by reinserting it in the SDXC slot, it never prompts for the password. Still able to mount it at that point using the Disk Utility mount command which prompts for and accepts the password while throwing the "Could not mount “AppleAPFSMedia”. (com.apple.DiskManagement.disenter error 49229.)" error. So it seems like there is something that happens in the mount process that gets "cleared" by the shutdown/restart process and then gets messed up again by mounting the disk.

I have a 2019 MacBook Pro and the Sonoma 14.1.1 install became stuck. Could not get it to reboot until I booted to recovery mode, unplugged everything from it and rebooted again. Now the hard drives are in various states of visibility. I have 5 that stay plugged in through a hub which are read only (formatted for pc) and one that is EXFAT. A couple of them I can see. Some I cannot see. Some are visible for only a second then I get the error message that they were removed without being ejected repeatedly (someone else above posted a photo of this). This last phenomenon includes the EXFAT drive, which was also not visible on my friend's Mac, but is visible and working fine on a PC. These are ALL USB-A drives that I have connected either via Hyperdrive hub or USB-A to C connection. It doesn't seem that there is a good fix for this, but I am including in case someone comes up with one. Based on everyone's experiences, it seems that the stuck update is likely unrelated.

Forget what I said above. I have found a workaround... https://forums.macrumors.com/threads/sonoma-wont-mount-external-drives.2404856/post-32562491

Booting into recovery mode, then mounting the drives using disk utility, seemed to fix whatever the problem was.

I hope this works for you, too.

I think the pivotal issue for mounting is about whether the external drive is encrypted or not. I have upgraded to 14.1.2 and still have this issue with SSXD cards as low as 1GB not prompting for the password needed to complete the mount. I also have an external drive that I use for backups that has several APFS drives defined on it and when I try to dismount by dragging drives to the trash everything seems to have worked (drives disappear from desktop and external drive indicates no activity) but when I unplug the drives I get the multiple error messages about the drives "Disk Not Properly Ejected". None of these drives is encrypted so this maybe a separate issue but clearly all is not well in the world of external drive support.

Does anyone know how to get this issue escalated or at least on the radar of the right folks at Apple OS? Seems like this stuff would be pretty major from a functional perspective and would merit immediate attention.

Not me. I am on a 2022 Macbook Air on M2 hardware. I am running Sonoma 14.2 The external drive (1TB Sandisk SSD USB-C) will mount on both PC's and my Mac Mini. It is formatted ExFAT. I ran first aid on the drive from the MacMini and then I could see the drive when I boot into utility mode. I have tried to then run First Aid again on the Macbook and that gives me one error. When I try to mount it on the Macbook I get a 119930874 error which indicates a problem with the file system. This isn't the issue since 2 PC's and another Mac will mount the drive and it works fine. Tech Supports answer was "Well reformat the drive".

Upgraded to Sonoma and then spent the next 2 days trying to resolve external drives not mounting. Tried all the work arounds on here to no avail. Tried reinstalling Sonoma to no avail. Tried creating a new admin user - still didn't work. Tried downgrading to a prior OS (Big Sur) - existing volume wouldn't let me downgrade. Spoke to an Apple support guy who told me I needed to reformat my external drive. You know what did work....I installed the latest NTSF for Mac by Paragon - drives mounted right up.

This worked for me but I have found that I must restart if I disconnect from the drive.

all of your disks are more than 2 or 3 Terabytes?? have the same issue in a M3Pro updated yesterday, only with disks above of 3T

Should not have to. However, you may need to give disc access permissions depending on the app. under privacy and security section.

I've got a 2023 Silicon MacBook Pro fully loaded with a Satechi hub set up that provides USB C to both A and C, with three hard drives connected. Two of the hard drives are C-to-C, and one is C-to-A. The same C-to-C connection always connects with the reboot and then works intermittently. If I re-boot, all three connect and remain connected as long as I'm working.

Somewhere between 10:00 pm and 6:00 am, the only one that stays connected is the same C-to-C connection always connects, and the other hard drives disconnect. I've checked the hard drive sleep, monitor sleep, and every option I can think of -- nothing fixes it.

I understand the latest release of Sonoma 14.1.1 (23B81) was supposed to fix this issue. It did not for me. Did it work for anyone? Why is my computer apparently shutting down and restarting, and that drops the harddrive connection?