Mac OS Sequoia not recognizing USB Flash Drives

Probably not what everyone wants to hear, but a new dongle worked fine for me. The old one still works on my older laptop on older OS

In my case the flash drive shows up in disk utility as Disk4.

In the Disk Utility you can mount it with the typed mount command, dismount or unmount is using the command and eject it using a typed command. It has a FDisk_partition_scheme of Windows_FAT_32

In Finder - Settings - General I have attempted the "Show these items on Desktop" and "Show these items on Sidebar" and the drive does not show.

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.

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.

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.

In Terminal, type the following:

ls /dev/tty./*

If you see something like /dev/tty.usbserial-xxx it may have found the USB port but can't communicate with it, if that makes any sense.

The xxx would be th port number

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.

Same issue here.

Disk has been in regular use with no issues until updgrade. Also works fine on second older imac also running sequoia

Disk shows in disk util but is greyed out and will not allow me to mount it

I tried mounting the disk using terminal but it gives me the following error:

mount: /Volumes/drive6s1: invalid file system.

Sys info for disk...



Re-formating as suggested in other threads does not work...

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 have "these problems" with external drives too on my Studio/Sonoma. That is why I did not upgrade to Sequoia yet. What's wrong?

After I bought MacbookAir/Sequoia two months ago, I thought: well I already have a TM drive (Orico, 2TB/WD Blue-SATA) for my Studio, so let's also make TM of Air on that drive. After that, the Studio did not 'like' the drive, it might show but later pop out again.

Also the Air could not see it anymore.

I think processes get stopped halfway. Or, because the Air really 'pressed' me to make a key for the disk (I thought it was for the file only . . .) , this is not recognized anymore by the Studio???. Anyway: the drive does not show up in Finder. On the Air I deleted this location for a TM backup. But the SSD, at that moment attached, "did not pick that up", it is not released so to say.

The disk does show up on my old iMac/Ventura, mounted, files are there, can be dragged to the bin, (not visible in the bin) but the process of wiping/reformatting disk (volume level or dusk level) with the utility is not possible.

On the Air that disk does not show in finder or DU, but when I pull it out it says it was mounted there.

Today:

One of my external drives, with photo's (2Tb NVMe), does not show in Finder - but Lightroom and Photoshop see the drive and can work with it. And Disk Utility shows it too.

These are problems that recur more and more.

For my Studio I bought a new Samsumg T9 as Time Machine disk. Sure it works. But why should I spend money? Changing to OWC of all my drives will cost me >€2.000.

yes Apple I like your way of thinking. Really amused.

But why don't you get smart (you have all the error codes at hand for me) and handle these errors. I think there are very easily to detect problems with threads that are conflicting, processes that stopped somewhere (because they take long we think we are finished. .) . You know what the Apple Support staff said: yes, you'll have to wait maybe 4 to 8 hours before it will mount. He laughed at my SSD enclosure (Orico) and mocked me on the choice.

But maybe, Apple, it is better you sort it out, and ask the user what/how to restore . . .

(ps I sent in a bug report of max 500 letters as no one reads this thread anyway)

My drives now auto-mount about 100% of the time after a re-boot.

Does macOS Sequoia go through some type of "learning process" where it learns what drives it needs to mount?

I'm on 15.1, but I did not see any improvement when updating to 15.1. I only saw improvement after a couple weeks of reboots.

Still the same problem.

It's not only a flash drive detection problem, but a huge USB bug.

No USB device are working anymore since sequoia, where everything was working like a charm juste before.

It seems to be relative to the way they manage usb communication.

It's a shame for the price of the device that I can't work anymore with it.

I will ask a refund, it's absolutely not acceptable.

I just purchased a new MacBook Pro with M4Pro and it has Sequoia 15.3.2 and my USB flash drive will mount fine.

I just upgraded my MAc Studio with M1 Max to Sequoia running 15.3.2 and that same USB drive won't mount. I am using USB-C.

Luckily the Mac Studio doesn't have any problems with my ProGrade Digital CF Express readers and my 2 External G drives. They all are using USB-C.

Confirmed: 15.01 still not connecting external drives/SD cards.