Q: Why won't my Mac Book Pro recognize my Flash Drive?

I had not had any trouble with USB drives until this morning. I renamed my flash drive. From that point on I could not access the drive from Finder. The name didn't show up in the lefthand column.

When I removed the flash drive I received the usual warning about ejecting properly. So, the Mac knew about the drive.

I did a search in "all my files" for a filename I knew existed on the flash drive. Sure enough, the search found the file. From here I was able to get to the drive.

It's a roundabout way to do it, but I can get to my drive so I'm happy for the time being.

Hope this helps.

I have the same problem, in my case is because all my USB Drives are in NTFS format, I found a solution (a pay solution) with this: http://www.paragon-software.com/home/ntfs-mac/download.html

The have a trial version, I hope works for you

This may be overly simple, but did you try flipping the flash drive over? I just had this problem and I had the drive plugged in upside down.

Me too. And it's reasonably specific.

I have a 64 GB Kingston Data Traveler with USB 3.0 and a WD 1TB, USB 2 powered drive; both have been set up with HFS and are encrypted. They're not detected by direct insertion to an iMac USB port (or via USB 2 or 3 hub). A 2 GB flash drive set up identically mounts automatically so I guess it's something to do with the drive size or power requirements?

Finder's Preferences 'External Devices'  and Disk Utility's 'Automatically open read-only images' are both checked/ticked.

I can mount the drives with Disk Utility, where  I -- as expected -- get the window asking for the pass but it seems a bit daft with a nice new iMac.

If you have any ideas, I'd love to hear from you!

Thank you. This solution worked perfectly for me.

I'm not sure if you are still having problems with this issue, but I found a solution. I bought a Targus 4-Port Hub from Walmart. This is what it looks like.

Thank you,

After several hours of reading useless threads your solution worked.

Since my flash drive is fairly new I recon my MBP usb drive may need a cleanup

The problem is not Apple as some suggested, it is simply USB 2 and USB 3 compatibility.

This problem appears mostly with older computers that have USB 2 ports and users trying to connect newer USB 3 storage devices.

Try connecting your flash drive through to a good quality USB hub that might do the trick if didn't work you need to check and see if your device is USB 2/ USB 3 compatible, if it is then contact manufacturer of the flash drive and report it as a fault  (if still under warrantee)

I never would have thought of this, but it worked for me with a "cheapo" hub I had sitting in a drawer from long ago.

Thanks

I'm having the same problem as well.  I have never had a problem with external flash drives before until recently I plugged mine in and it said that it was unreadable or something of the like.  I figured that it was the flash drive because it's kinda old and cheap.  I dug out an older flash drive that I have used with the computer before and tried that.  When I inserted the flash drive into the USB port, nothing happened.  I have been into Disk Utilities to make sure that the "automatically open read-only images" has been checked and I checked my Finder preferences to see if external disks was checked as well.  I have just upgraded to the new OS X Yosemite and my computer is an iMac (mid-2007) version 10.10.

Oddly enough, I had the exact same problem with my NTFS-formatted USB drive. But after slowly sliding the USB drive in place, it recognized the USB drive. Weird.

I have had this problem in the past.  I saw somewhere (sorry I don't still have the thread) that if the flash drive is too powerful, Mac will protect itself from letting it connect.  I worked around the issue by using a USB hub as the middleman between the flash drive and Mac.

I tried the "slow" insert technique and it worked! Why I can't explain but thanks for the discovery!!!

The slow insertion technique for my USB 3.0 Corsair Survivor worked on my mid-2014 MBP running Yosemite 10.10.2!

EDIT: It was FAT-32 formatted not NTFS like most are having issue with so I can read/write.

wow -- this really is the solution for me as well, synepdx -- very weird!  But I'm with some of the others -- seriously can not believe such an expensive computer has problems like this -- never had this on any other device unless the flash drive went bad.  Thanks for contributing, synepdx!!