Unable to eject or erase USB drives

disk-utilityfinderusb

I'm unable to eject USB drives. When I try, I get this error:

The disk "Untitled" wasn't ejected because one or more programs may
be using it.

To eject the disk immediately, click the Force Eject button.

Additionally, when I use Disk Utility to erase a USB drive I get this error:

Disk Erase failed with the error:

Couldn't unmount disk.

This happens on my account and my wife's account. I can partition USB drives, but I can't erase or eject them.

Any ideas on how to resolve this?

Best Answer

When you have this kind of error, typically it occurs because the device is mounted and there is something accessing the information on the mounted disk. Whatever is causing you to be unable to eject the disk is the same reason the disk utility can't unmount the drive to erase it.

Likely culprits for things still accessing your files include applications like Preview or possibly Dropbox if you use it to import the information. If the USB drives include songs, iTunes could possibly be accessing the information as well. You want to make sure that all of these types of apps are closed when you go to dismount.