Uh-oh! Is your Mac failing to recognize your flash drive? Maybe you’re about to give a big presentation at work and the thing’s not working, or perhaps you’ve brought some cool movies to your friend’s house to swap and it’s giving you grief. If your USB thumb stick isn’t working when you’re at the end of your tether, well then it’s time to get to work quickly to fix it.
First port of call: check that the flash drive actually works by trying it on another computer or USB-enabled device that will recognize it such as your TV. If this works, then it’s something to do with your computer. If it doesn’t, then it’s something to do with your USB stick.
Here are the main reasons why this pesky error is occurring and your drive isn’t reading, and ways how to fix your flash drive when not recognized by Mac.
Do note that you will only need to try the steps in the USB Issues section if the flash drive itself is malfunctioning, and follow the steps under Computer Issues if the issue is with your computer.
Test to see if your USB port is working correctly
Unfortunately, if you’ve got a Mac and if you have a newer model, you may only have one USB port. If this USB port is malfunctioning, then sticking your flash drive into it may not work. Remove the flash drive and insert it in very slowly to see if your computer now picks it up. If you absolutely need to use your Mac, grab a lightning to USB adapter and plug in your stick this way – but check first to determine that it’s not a different issue before you go ahead and make an unnecessary purchase.
Reset your PRAM
A quick fix that can sometimes work for this issue is resetting your PRAM. Press the following combination of keys to do just that.
Update your system software
It is possible that your USB drivers are outdated if you haven’t turned on auto-updates for your computer. To update, select the Apple logo on the top left corner of your screen and then press “Software Update…”. Download the available updates and check if your flash drive is now functioning.
Update your Operating System (OS)
Has it been a while since you’ve updated your operating system? Upgrade your OS to the latest version of OS X. At the time of writing, the update available is OS X El Capitan. After the update, check to see if your USB stick is working.
Your USB drive is not working as it should
You may need to manually connect your USB to your computer. With your USB inserted, select Applications > Utilities to start. From here, select Hardware > USB > USB High-Speed Bus > Hub > USB Display Adapter.
Where devices are listed, select your device name and the option “Ask me what to do”.
Now go to the Devices menu, and choose External Devices, and choose your device name from the list.
The firmware on your USB is corrupted
If your USB is corrupted, then you’re either going to have to repair or reformat it, which will wipe the data contained on the disk. If you need to recover your files, you can use Wondershare’s Data Recovery program to (thankfully!) find and recover all the files from your disk.
Here’s how to either repair (if available) or format a corrupted disk so that it works again.
Head to Applications, then Utilities on your computer. Under Utilities, select Disk Utility.
Find your USB listed in the column on the left side of the Disk Utility app.
See if there is an option to Repair Disk. If available, select to repair and then attempt to have your USB recognized again. If not, select Verify Disk and follow the steps. If neither of these works, then select Erase in the horizontal menu across the top to go and format the disk.
Select erase to format the drive and erase all content. Make sure that you follow up this step by completing the recovery process so that you can get back all the data on your disk.