tried to erase a mac drive got could not unmount disk

Reasons for Mac not reading external hard drive On macOS Big Sur, the error will read slightly differently: 'the disk you attached was not readable by this computer' - but it’s essentially the same thing. When you connect an external hard drive, a USB, or a SD drive to your Mac, the following error might pop up on the screen: 'the disk you inserted was not readable by this computer.' It usually occurs on macOS High Sierra, Mojave, and Catalina.

Instructions on how to fix it when your Mac won’t read a disk.

Reasons for Mac not reading external hard drive.

In this article, we'll explain how to fix corrupted hard drive, how to make a drive with an incompatible file system readable, and other methods to avoid the error on your Mac. Even more, you can fix the issue with the drive and continue using it.

We assure you it’s possible to recover data from that drive even in the worst-case scenarios. When you have important files on the external drive you're trying to connect, but your Mac shows an error saying 'the disk was not readable' - don’t panic. Get an ever-growing collection of troubleshooting apps.

Tried to erase a mac drive got could not unmount disk