Mac OS Sequoia not recognizing USB Flash Drives

having issues with external SSD's not mounting or visible . Also SD card not showing up or mounting on reader on my new Mac Studio M2 Ultra. New this week, all worked well on Sonoma, until I upgraded... Not impressed.

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?

Regards, Brian

DavidWMB wrote:

I reported the matter to MacOS Feedback, but Apple hasn't bothered to respond.

You did well to report it. There is never a reply unless they need further information. That's normal procedure, all feedback is read but usually they do not reply. The more people join their voices with respect to a given issue, the more likely it is to be fixed sooner.

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

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. Especially for someone like me, who has a very basic understanding of how tech works. Trogander, you lost me on step 3 but I do appreciate all the detail you provided.

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

UPDATE

Bought the new OWC Express 1M2 and it works at a fantastic rate.

Both read and write are well above 3000mb/s. So it was a defective enclosure of some sort. But rather odd that it worked on all of my older OS X systems...

I had the same issue with a USB Key (originally formatted from Win). On Sonoma it was working fine but it was not auto mounting on Sequoia. I did re-format it on OSX and now it is recognized and auto mounted.

Sequoia also fails on both intel iMA and M1 macbookpro, when copying very large folders (with thousands of files), with error 50, every time. However on a Sonoma macbookair it works every time, for the same folder, on the same drive, on the same network.

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.

Tueso wrote: "Have any of the apple support team seen this post?"

Doubtful, considering thousands of daily posts and these being user-to-user communities. Use this form:

Feedback - macOS - Apple

õ¿õ¬

Closely related issue ... when re-booting, my external drive will not auto-mount.

2019 iMac 27-inch; Sequoia 15.0

Any thread dedicated to this issue?

They ARE encrypted. And strangely, they actually automount about 10% of the time! Intermittent issue! Hard to debug!

A Store N Go very old USB is recognised after installation of Sequoia

The external is not recognized the external does not show at all in Disk Utility. That is what is happening.