This answer explains how address the error 'Couldn't umount disk' when using Time Machine.*END A drive format or erase from Time Machine fails with the following error message: There was an error preparing the Time Machine disk Couldn't unmount disk The error message occurs when the disk is being accessed by a running process on the computer. • Click the Apple Icon in the upper left corner of the screen as shown below • Select System Preferences • Click Time Machine • Turn OFF Time Machine or • Power OFF the computer • Disconnect the drive from the computer by removing the USB cable. If your drive is a My Book, please also power off the drive by removing the power cable • Power ON the computer • Re-Connect the drive.

WD passport external HD not recognized on windows 10. Download gbc emulator. My OS is 64 bit. I tried solution of uninstalling and then installing HD but it didn't work. Please suggest how to resolve this. This thread is locked. You can follow the question or vote as helpful, but you cannot reply to this thread.

If this drive is a My Book, please also connect the power cable • Open Disk Utility. Please see for help • Erase or format the drive. Please see for help • Please see for help setting up Time Machine with this drive.