In order to replicate the issue just connect any external SSD wait for a while and it will be disconnected with message "Disk Not Ejected Properly". SSD is connected to M1 MacBook Pro. It's neither a cable issue because I tried multiple cables, nor an SSD issue as everything worked just fine before upgrade.
Here is the issue that I've raised https://feedbackassistant.apple.com/feedback/13263285
I believe that if we raise couple more similar issues Apple will notice it, because the one that was reported by me - says : Recent Similar Reports:None
When you post here, Readers are other users like you. Apple does not troll the forums looking for issues. Apple does not understand the urgency of this issue unless a LARGE number of Users let them know it is an issue.
Be sure you have either contacted support here, in hopes of getting more help:
or posted a product feedback of type "bug report" here (but these are Not tracked and no response will be forthcoming):
When you post here, Readers are other users like you. Apple does not troll the forums looking for issues. Apple does not understand the urgency of this issue unless a LARGE number of Users let them know it is an issue.
Be sure you have either contacted support here, in hopes of getting more help or creating a Bug Report:
or posted a product feedback of type "bug report" here (but these are Not tracked and no response will be forthcoming):
Please make sure to report your problem on feedbackassistant.apple.com as I did for my SSD problems! We only stand a chance if we mass report it, so Apple hopefully will take notice of this! Please report it! It only takes a few minutes, and it will make a difference for sure! The more reports about this, the more chances of someone noticing it!
I had the same exact thing with the ScanDisk portable extreme 1TB, but the problem is with the drive itself, the controller is a bad quality one, after a while it totally died< had to open it to get the drive itself out of it and install it to an external ssd enclosure to rebuild the file system and retrieve my data, just be careful with these Sacndisk drives.
Before 8 Dec 23, I had Mac OS Ventura and things were smooth between my External NVME drive and my Mac mini m2 pro. But as soon as I upgraded it to Sonoma things between my drive and machine went bad.
My external Nvme drive keeps getting ejected automatically, at start I thought I may have moved the enclosure, but it was happening again and again.
Steps to confirm its the bad update about thunderbolt port in SONOMA.
So conclusion, its definitely something wrong with the Sonoma update about handling power or data on thunderbolt ports (I tried on 2 different ports ).
So I will be using the drive on USB 3.0 port until they resolve the issue in next updates , hope so.
I have a similar issue since the upgrade to Sonoma on my MacBook Pro M1. Two SanDisk Portable Extreme (one 1TB, the other 4TB) cannot be used properly. A copying process of about 60GB to the 4TB SSD all of the sudden stopped. From that moment on the SSD couldn't be unlocked anymore (see screenshot). I had to buy an expensive Data Recovery Software that worked on M1 and started recovering Video Footage and copying it to my other SanDisk Portable Extreme 1TB (it was the first time it was plugged into the MacBook after Upgrade to Sonoma). Copying process went well. The next time I plugged the 1TB SSD in it would take long to load the SanDisk Unlocker, unlocked it, navigated to the folder, it would load the content of the folder (like on a ancient windows 95), load, load. Then the drive disappeared from Finder without an error message or notification. Retried a hundred times. Sometimes it doesn't disappear but it loads forever(!) and I cannot preview files. When trying to preview a file it again loads of a minute or more and than fails to preview, sometimes the content of the entire folder just disappears in Finder. It's so weird. Ive been working with these two expensive SSDs daily on my MacBook Pro before the upgrade and never had a single issue.
For me connecting ssd drive on usb 3.0 port with USB-A connection is working fine.
The problem is with the thunderbolt usb c type port when we upgrade to SONOMA.
I tried all of these options except changing the enclosure and none of the really helpful. It is not a coincidence that in Venture everything works fine. So the issue is on apple side and I raised a bug to fix it.
What OS were you on before? I'm interested because I was (maybe still am, not sure) convinced this was a hardware (ports) issue on my Mac. I've had the identical issue on both Monterey and Ventura, but it's not just SSDs, it's my RAID and 2 x 7200 rpm backup drives as well. It stopped completely for several months after all 4 USB-C/thunderbolt slots were replaced. I stayed on Monterey but the problem gradually returned. Mac has been sent for twice since then. Last time they replaced the logic board and internal SSD but not the ports and upgraded OS to Ventura (I refused to agree to Sonoma because of all the issues I see reported here). However the problem continues on Ventura. It's less frequent than before, but definitely not cured.
Like you I do all my processing (photographer) on external SSD and this is a nightmare. (Also a nightmare for backups of course).
Update: I was having this same Issue with my fairly new Kingston XS2000. I chatted with Apple support and opened a case. We tried a few basic things and the drive kept failing to run First Aid. I ended up backing up the drive and reformatting it. Since then I have had zero disconnects. It seems like the drive got corrupted in some way when I did the OS upgrade to Sonoma. I bought this drive new while on Ventura so this is the first OS upgrade. It was annoying to have to reformat a 4TB drive but in the end fixed things.
Same thing for me with an external HDD used for backups. No issue until I upgraded to Sonoma, no issues during the day when the machine is in use, but at night multiple improper disconnect messages. Interestingly, the problem goes away if I connect the drive directly to one of my laptop's USB-C ports with an Apple USB-A to USB-C adapter. (previously I've had it connected to a Thunderbolt dock along with other peripherals.) I've tried different docks and the problem always exists if the drive is not directly connected.
Also, even if the drive is unmounted in the evening, the message still pops up. This suggests that the hub/dock is getting powered down, then powered back up, which would cause the Mac to 'see' the drive and remount it, then improperly disconnect on the next power down.
It's also not a coincidence that so many people have described it happening on multiple drives – including me (4 external drives, different models, different ages). Like you I've done the dance with cables, removing hubs etc. I also have various other issues including problems with dictation, which Apple genius bar diagnosed as being due to intermittent (wired) Internet connection via Thunderbolt ports. I'm still having this problem although I have yet to upgrade to Sonoma. I don't know enough about the relationship between hardware/software/firmware but I can't help thinking there is something else at play because it is not just Sonoma.
It's not just SanDisk. I have the same problem with a 4TB Seagate SSD. I'm concerned that some files and folders are being corrupted by this, but it's difficult to tell when the problem occurs. It's rarely while I am activity working at my laptop and most often when I return after the screensaver has come on and maybe the Mac has put itself to sleep.
Same problem with Sonoma 14.3.1 on a new (Nov 2023) MacBook Pro M3 Pro Silicon. Happened infrequently but many times with a 5T external HDD. Tried 3 different cables (USB Micro B to USB A into the USB A female to USB C adapter), happened on all 3 cables. Tried a different 5T HDD, happened with it also. This never happened with either of these same HDD on my old laptop (MacBook Pro mid-2014 with Mojave). Today It has happened a dozen times in one afternoon with a Lexar 128 GB USB flash "thumb" memory stick. I tried 2 different adapters, right and left rear USB-C ports on the laptop, happened multiple times in every configuration. Results suggest to me a bug in Sonoma. When it happens while copying to the Lexar, I get "device disappeared", then a separate alert "not ejected properly".
The only thing I know, is that the issue appears since I've upgraded to Sonoma and only when I use nvme drive. My machine is m1 MacBook Pro, and I've never experienced such issues with intel mac's. When I use slower ssd's 2'5 + external enclosure -> everything works fine. Not sure whether it's a hardware or a software issue but it's somehow related to thunderbolt ports.
External SSD keeps disconnecting after upgrading to Sonoma
