Mac OS Sequoia not recognizing USB Flash Drives

PVRP wrote:

I have a similar issue with M1 Air and Sequoia (after updating), my external SSD in a HUB is not mounting.

The fix is to activate the option in security, always ask to connect accessories. Not ideal, because now a I have to allow everything I plug.

Once it asks about the one device, you can set that back to something else. It should remember the devices you approved.

PVRP wrote:

The only way it works with this SSD is with the option I mention. If I change to anything else, it doesn't mount.

Recognizing and mounting are two different things. If it doesn't recognize it, it certainly won't mount.

I would reformat the drive.

Just to add to the confusion, running MacOS 15.1 on an M1 Mac Studio, after the last update, it won't mount SD cards from any of my Fuji cameras, but it will mount SD cards from my Leica. The same thing happens with my M1 Mac mini running the same MacOS. The cards are visible in Disk Utility, but they won't mount.

I am also having the same issue. I am using a Cruzer Fit drive, plugged into a USB-C adapter formatted to MS-DOS FAT32. Prior to this upgrade it worked fine, I have many files on this drive and could access, update and save with no issues. After the upgrade the drive does not show under locations in Finder; however, when I go to system information -> hardware -> USB it shows there under USB 3.1 Bus. Also, when I select a recent word document saved on this drive it gives an error that the file can't be opened. Frustrating as I plug the drive into another MAC and the drive shows in Finder and I sent some of the files through email. tried many reboots but the issue still remains, hopefully fixed soon.

I'm having the same problem and my LogiTech webcam won't connect via the USB port. Both USB drives and the web cam try to connect but will not stay mounted. With the USB drives I get repeated "Disk Not Ejected Properly" error messages because the drive connects for a second and then disconnects. The web cam seems to to the same thing. I've tried different USB ports on my Mac Mini and the result is the same. Updated to Sequoia 15.0.1 with no change. When I use iPhone mirroring I can use the iPhone as a web cam via the bluetooth connection. But the USB ports are the problem in Sequoia.

USB C adapters got my web camera working, too. All USB devices are plugged in to a USB dock that is connected via a USB C adapter. Working fine, now. Apparently the bug is in the regular USB port drivers.

I considered rollback to Sonoma using Time Machine. But when I called up Time Machine the only backups visible were ones made AFTER the installation of Sequoia. Have no clue how to sort that out, but Sequoia is not ready for prime time.

Brian Williams2 wrote:

Hi. You wrote "Allow accessories to connect,". I am on 15.0.1 and cannot find this option in Privacy & Security. Apple documents say it's there, but I don't see it. Where did you find it?

I believe that option is only available on the M-series laptops. The M-series desktop systems I don't believe have that option, nor do any of the Intel Macs (laptops or desktops).

Hey all, so I have a very strange issue. Similar to the other posts. I have a Samsung T7 ssd it is not recognised at all with my Macbook M3 Sequoia 15.0.1. When I plug an older SanDisk extreme it is recognised.

When I plug in the T7 with a USB c - USB c charging cable the drive is recognised. But obviously the data is very slow so not usable. I have tried the same hard drive with my ipad on ios 18 and not recognised. Plugging in the same hard drive in my mates ipad ios 17 it works.

I have been on the phone with apple support to bring this issue to them mentioned this forum. So hopefully something comes out of my hour on the phone.

dwiser12u wrote:

I had to go through Apple Support. They say they don't have any history of this issue with updating to Sequoia.

Probably because people are not contacting Apple directly for support. Apple won't know about any problems unless people make official support cases with them.

After trying many things, the support person had me upload the files from my Flash drive to my old computer, then using my MacBook Pro to erase my flash drives (that were already in FAT-32) and reformat my Flash drive with ExFAT. And finally, reload my flash drives with the files from my old computer.

It seems like a lot to have to go through for a system update.

If a drive is partitioned & formatted using another system, it is possible the other system configured the drive or file system in such a way that macOS does not understand. Other operating systems typically have more options for file systems than macOS does. Plus Apple rewrote the FAT/exFAT drive in macOS Sonoma which introduced some compatibility issues...any time a file system driver (or any driver for that matter) is created, it takes a long time to find all the bugs in it.

I make it a rule to always partition & format drives before using them in order to get rid of the factory image which could contain something that could cause problems. This way I know the partition & file system are compatible with my computer.

Plus, I had a USB stick which appeared to work fine when used with just a single computer. When I tried to use that USB stick on another nearly identical computer (only differed by a different version of macOS) I could not read the USB stick. Same thing happened in reverse if I erased the USB stick on the 2nd computer....the first computer could not read it. Found out the USB stick had a hardware issue.

On my Mac Studio M1 with 15.0.1 external flash drives (SD, CF) are not recognized. Diskutil does not show them with USB readers (I've tried 3 different). But the SD card slot on the Studio recognised a card.

On my MacBook Pro M2 with 15.0.1 everything works fine.

MJ wrote:

dwiser12u wrote:

I had to go through Apple Support. They say they don't have any history of this issue with updating to Sequoia.

That's bogus. Either Apple is lying or they maintain very crummy records.

I chatted with Apple Support for about 40 minutes on or around September 25, 2024. No solution, but the tech had me try a bunch of stuff, including re-booting into Safe Mode.

I also reported this on Apple Feedback (link posted somewhere in this thread) on or around October 1.

They must be joking, it works with the original braided iPhone cable.

Since I upgraded to Sequoia, my T7 stopped connecting despite all the advices in this topic. I only used its original, thick and genuine cable. It turns out that now it only works with the iPhone's original cable...

If anyone knows a workaround to this, I'd appreciate it.

I confirm critical erratic behavior for ALL my USB devices plugged on my macbookproM2 after upgrading to Sonoma and complete blocking after upgrading to Sequoia. Never experienced such failure since my Apple II+. Prior focusing on IA may be more wiser fixing these USB issues.

Well, got my M4 Pro MBP yesterday and, as expected, my 2TB Kingston KC3000 SSD in the IcyBox enclosure was not detected (just like on my M1 Pro MBP with Sonoma). Started a chat with Apple support, went through some 4-5 advisors, even being called over the phone. No solution other than check your SSD for errors, try another one and so on.

Decided to further experiment, so I plugged the IcyBox in a TB powered hub (the mighty OWC Thunderbolt Hub). Worked like a charm. Decided to take things even further, so I plugged in my small D-Link DUB-M6100. Also plugged the IcyBox and.... wouldn't believe my eyes... it worked.

Since the OWC is nothing to consider hauling around when touring, and the D-Link fits in a pocket, I am at least happy to share this with you, hoping you'll also find it helpful.

From my standpoint, I reckon that Apple has not yet optimized the power delivery via the TB ports in Sonoma and Sequoia (albeit the problem has been around for quite some time now). Hopefully they F***ing Will, because otherwise it could become a laughing stock.

Also, using the USB-A connector of the IcyBox cable resulted in a no-show for the SSD; it looks like only USB-C does the trick.

Clearly a power management issue on behalf of Apple, but something that needs to be reported over and over until they finally fix it.