Windows are accessing folders on the disk. Make sure there are no applications currently running from theĭisk you want to initialize.Alternatively, if you have theįinder set to display disks on the Desktop, you can drag the disk to The left pane of the Finder toolbar window, an eject button shouldĪppear to the right of the disk's listing it looks like an up-facingĪrrow with a line underneath it.

Try to unmount the disk manually from the Finder.

If you are still having trouble unmounting the disk, try the To boot from a CD, DVD, or different hardĭrive, see ARCHIVED: On a Mac, how do I change my startup volume or boot from an You should always boot from a drive other than the one you're trying Initialized if the drive is in use, it cannot be unmounted, and thus A drive must be unmounted or taken offline before it can be This error means that the hard drive can't be unmounted because a file May get an error message about the program being unable to unmount the I could see it in Disk Utility (on both OS’s). It would say all good, but the drive would NOT mount.

In Mac OS X, when you attempt to initialize a disk withĭisk Utility or a third-party drive formatting utility, you Time machine external became unmountable in (running El Capitan) but I also tried it on a different mac running Leopard (yes,) still didn’t mount. Information here may no longer be accurate, and links may no longer be available or reliable. This content has been archived, and is no longer maintained by Indiana University.

Mac os could not unmount disk