How to Fix a USB Drive That Only Opens on One Computer

A USB drive works fine on one machine and shows nothing, or an error, on another. The cause is almost always the format, encryption, or a missing drive letter. Work through these in order.

Check the format

On Windows, right-click Start, choose Disk Management, and find the drive. On a Mac, open Disk Utility and select it. A drive formatted APFS or Mac OS Extended will not open on Windows. A drive formatted NTFS opens on Windows but is read-only on a Mac. FAT32 and exFAT work on both.

Reformat as exFAT

Copy everything off the drive on the computer that can read it. Formatting erases the drive.

On Windows, right-click the drive in File Explorer, choose Format, set File system to exFAT, and click Start. On a Mac, select the drive in Disk Utility, click Erase, set Format to ExFAT, and click Erase. Copy the files back.

Look for BitLocker

If the drive asks for a password on other PCs, it was encrypted with BitLocker To Go. Enter the password, or unlock it on the original PC and turn BitLocker off from Control Panel, BitLocker Drive Encryption. Macs cannot read BitLocker drives without third-party software.

Assign a drive letter

If the drive appears in Disk Management but has no letter and does not show in File Explorer, right-click its partition, choose Change Drive Letter and Paths, click Add, pick a letter, and click OK. This happens when the letter it wants is already taken by a network drive or another device.

Try another port and check the disk

Plug the drive into a different USB port, ideally one on the back of a desktop, and use a different cable if it has one. Some ports do not supply enough power for portable hard drives. Then right-click the drive in File Explorer, choose Properties, Tools, and click Check to scan for file system errors.

If the drive is failing. Slow opening, clicking sounds, or errors that come and go on every computer point to a dying drive. Copy your data off immediately and replace it.

If you move between Mac and Windows. exFAT is the format that works everywhere, including TVs and game consoles. Use it for any drive that travels.