Unable to read USB thumb drive

Back vs. front of computer USB port

If you're connecting the USB thumb drive to the front of the computer or to a USB hub, try using the USB port on the back of the computer instead. Because the USB ports on the front of a desktop computer are passive USB ports, some flash drives, such as a Lexar JumpDrive FireFly will not be detected when connected to the front of a computer.

Bad USB port

USB cable and portVerify if it's your computer or the USB thumb drive that won't read, by trying to see if the thumb drive works in another computer.

If another computer can read the USB thumb drive, but your computer is not able to, try the suggestions below.

  1. Try a different USB port.
  2. If you're connecting the thumb drive to a USB hub, try connecting it directly to the computer instead of the hub.

Older computer

Older computers that are using USB 1.0 may not be compatible with some thumb drives meant for USB 2.0. Make sure your computer has the latest version of USB, if this computer has never been able to read the thumb drive.

PC vs. Mac thumb drive

There can be compatibility issues when attempting to read a PC formatted thumb drive in a Mac, and a Mac formatted thumb drive in a PC. If the Thumb drive is working in one computer, but not the other it's likely it's been formatted using NTFS and cannot be read on the Mac or formatted in HFS and cannot be read on the PC. In order to get both systems to read the drive we suggest formatting it as FAT32 or MS-DOS using the steps mentioned below.

Notice: Formatting a drive will erase any of the contents of that drive. If you're able to read the data on the drive on a Mac or PC, we suggest saving that data to the computer before formatting it.

Windows users - Format drive

  1. Open My Computer
  2. Right-click on the USB thumb drive icon.
  3. Click Format.
  4. In the Format Window select the format of either FAT or FAT32 and click Ok.

Mac users - Format drive

  1. In the Disk Utility section for your drive, format the drive as MS-DOS.

Bad USB thumb drive

If you've tried all of the above suggestions and the thumb drive cannot be read in multiple computers, it's likely that the USB thumb drive is bad and will need to be replaced. Any information on the drive that has not been backed up elsewhere is lost.

Additional information

  • See the thumb drive and USB definitions for further information related links.