3

I'm trying to format my USB so I can get all the space back onto it, but every time I try to erase it in Disk Utility, this comes up:

POSIX reports: The operation couldn’t be completed. Permission denied

  • Are you erasing the disk or the main partition? – Harcker Nov 6 '17 at 9:50
1

Try with diskutil:

diskutil eraseVolume HFS+ "new name" disk1

Replace new name with the name you wish the disk to have, and disk1 with the disk identifier (select disk → Info).

  • tried this method, but got Error: -69888: Couldn't unmount disk – Micah Stubbs Feb 25 '17 at 4:29
  • Try force unmounting by entering diskutil force unmount disk1 in terminal. – user244378 Nov 6 '17 at 9:28
-1

Although it may seem unintuitive, try formatting the drive using a Windows computer. Then, take the now (Windows) formatted drive over to the Mac and format it there - it will work.

It's has happened to me many times too, but the speed of this method has always greatly outweighed any further research time.

I hope that helps you out, however, the question of what causes this error could be one of many... hence, if you need a formatted drive now, this will work.
But do let me know how you get on.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .