This error occurs differently for the people but the solution is almost the same. Erase process has failed couldn’t unmount disk.Erasing “Untitled 3” and creating “Untitled 3”.This guide is going to assist you to figure out this matter. You see this error message when you want to erase a partition on Disk Utility.

If you want to fix it then navigate to your windows operating system and open Disk Management. Create a new volume and choose the File System “ exFat“. #Could not unmount disk external hard drive how toĬheck the step by step guide on how to create a new volume on Windows 10. Once the partition has been created, boot into the macOS High Sierra Bootable USB installer.

Or if you are trying to build a Hackintosh and having this problem then boot via USB installer.

MUHAMMED WASIM JAVEED VONTIMETTA Februat 5:06 AM ReplyĪny answer to Brad’s query, same here as well first aid is OK but when erasing giving the error as unable to write to the last block ….

Mukhtar Jafari Post author Jat 10:43 PM ReplyĪlso if you guys are interested in video tutorial please visit our video on Youtube.

I have a Sandisk Ultra USB Flash Drive that became Read Only on my Mac. I can use and access what is on it but can not add or delete Files. Sandisk accepted my Warranty request for a new Flash Drive. They sent Me a RMA Shipping Label to return the Drive. The trouble is I have a lot of Private information on it so I don’t want to send them the Flash Drive. Unhappily I continue to get “failed”, with the log saying “Couldn’t unmount disk: (-69888) I’ve tried Erasing the Drive using the Disk Utility several Times and always it fails to Erase or reformat.

Michael Gonzalez Jr Maat 12:25 AM Reply.

#Could not unmount disk external hard drive mac os x.

#Could not unmount disk external hard drive how to.

Mac could not unmount disk