Flash Drive No Longer Recognized

Had same issue (3 different flash drives) - shows in system info under USB, but not in finder.

None show in disk utilities.

Recognized in Windows on VMware, so formatted it exFAT in Windows - same no-show issue in MacOS

Booted to recovery (command R) and ran disk utilities.

Show up in disk utilities in recovery mode, and did repair - GAVE EACH A NAME, then reformatted exFAT

All 3 had no name

After returning to MacOS, each USB drive now appeared on desktop and in Finder.

I believe it was because the USB's had no volume name.

One was a USB-C, other 2 were traditional USB 3.0 and 2.0 drives (with Apple C adapter).

My unit:

MacBook Pro touchbar with 4 USB C ports

MacOS 10.12.4

How did you encrypt it?

I assume it was a case of right clicking & selecting encrypt so that Disk Utility did it for you? This is using Apple's Filevault, but it is only supported on certain OS X versions as you are finding out.

Do you have any backups of the encrypted contents?

You can't rely on the Finder showing connected disks, open Disk Utility (from Applications/Utilities/) and see if you can see the USB device listed in the sidebar. If it is there select the disk & try mounting it. You may also want to try mounting the partition (below the disk).

If the disk doesn't work on 10.9 I'd consider erasing it and starting afresh. That is assuming it is visible in Disk Utility.

If you start over reformat the disk & select the 'Mac OS Extended (Journaled, Encrypted)' for the format. This will encrypt before you use the disk which may work better than encrypting 'in place'.

Failing that I would erase on 10.whatever & start again on 10.9.

Finally if it doesn't want to erase or appear at all I'd consider returning it, sometimes things just inexplicably die when they are new.

Another option is Truecrypt, which is multiplatform & supports older OS X versions. However the developers recently gave up developing it & started putting out scary messages. It may still be OK if you can use the version before 7.2 (it's too much politics to explain).

One thought…

Where are you connecting it? Certain USB ports are low power & some devices need a higher current so they fail to mount, it's normally the keyboard ports.

Usually there is a dialog that warns you about it.

Just try all your ports on the iMac.

If the system information USB section isn't showing the device at all that seems like a low level failure to me, not just a bad partition.

Make sure you refresh that window as you remove & attach it - the view isn't live! It's cmd+R or in the File menu.

Did you ever get a satisfactory response to this?

I too have just encountered this issue. I have a PNY USB 3.0 128MB flash drive. I used it successfully for several months.

Today, connecting it to a brand new Mac Mini, 10.10, it is not recognized. It's not just that it isn't recognized... It's not even showing up in Disk Utility. The only indication I have that the system has detected it is this log message:

2014-10-26 12:20:55.000 PM kernel[0]: USBMSC Identifier (non-unique): 09031000003796153712 0x154b 0xfa05 0x1075, 2

Also, it shows up in System Information, in the USB Device Tree, but nowhere else.

I then tried it in my Retina MB Pro (2.3GHz i7) running 10.9.5, where I had always successfully used it, with the exact same results.

It appears that the OS is failing to load the driver, or perhaps something in the USB negotiation is failing.

I tried it on a couple of Macs, running 10.9.5, both USB2.0 and USB3.0, with no luck. My old Snow Leopard 2005 iMac recognized it, but the filesystem was too new for it to read it. (It is an encrypted USB volume). I was, however, able to copy the raw disk image, even though that mac couldn't read it. I am hoping to access the files that way.

Now... I just put the USB Key into another of my Macbook Pros, an old 2.33GHz Core2Duo running 10.7.5, and this machine was able to access the encrypted partition with no problems at all.

So, I conclude that this is some problem related to 10.9.x, since both USB2.0 and USB3.0 Mac's running 10.9 were unable to recognize the disk, yet a 10.7.5 machine with USB2.0 reads this disk fine.

I'm hoping to get a suggestion from someone on how to best go about finding the root cause of this issue...

Thanks,
Pat

Try booting into the Safe Mode using your normal account. Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up after waiting 10 seconds. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear and again when you log in. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application un-installer. For each disable/delete, you will need to restart if you don’t do them all at once.

Safe Mode - Mavericks

Safe Mode - About

I also was having the same issue with the PNY 128 gig flash drive. I have one Imac running Yosemite 10.10.2 and an older Imac also running Yosemite but version 10.10.1. The Imac with the 10.1 version could recognize the flash drive but not the 10.2 version (It used to!). I re-partitioned the drive by using the Disc Utility app, selecting 1 Partition, clicking on Options and selecting the GUID Partition Table option. I used the MS-DOS (FAT32) format option. My Imac, 10.2 version, now recognizes the flash drive. Hopefully the fix will last.

I've had a long discussion with PNY about this. In my case and on many different computers I tried with 10.8, 10.9 or 10.10 they don't show up or drop off after some time because the contacts portion of the flash cannot go in far enough or too much "wiggle room" in the usb slot. We isolated by using an Active USB extension cable which made it appear on all computers instantly vs no extension cable and it wouldn't appear at all.

So I ordered a less expensive 1' extension cable (non-active) but it didn't work. So I'm not spending the money for additional active cables and instead returned my PNY 128GB and ordered a different brand. These new ones are working fine.

I just bought a PNY 128GB 3.0 Turbo flash drive today and I have exactly the same issue. System Info seems to detect the drive but it still doesn't appear on the desktop. I've tried this on OS 10.7.5 with a MacBook Pro and with Yosemite on a 2013 Mac Pro. I won't deal with extension cables since that defeats the whole convenience factor in using flash drives. I have an email into PNY but most likely I'll return this to Best Buy and find something that works.

Can you see the drive in Disk Utility?

See mount section in 1st linked article.

Disk Unmount Using Terminal

Disk Utility – Force Mount Disk