Error: "couldn't unmount disk" keeps coming up when formatting external HD to eXFat

I have a WD "my Passport" external HD that is currently formatted for a PC and I would like to format it to eXFAT. Every time I hit "erase" in disk util it just comes up with the error "couldn't unmount disk". Btw, I am running on Maverick. Can anyone help me with this please?


Solution 1:

I had the same problem with the same drive. I finally got it to work by rebooting from the recovery partition and formatting it using the disk utility option.

Solution 2:

It's proper for the operating system to not unmount a volume if there is, on the volume, an open file that can not be closed.

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The accepted answer to The volume can't be ejected because it's currently in use

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The Mac App Store page for WhatsOpen

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