It’s possible you’ll hit an error at any one of these points.įor instance, some readers report receiving the message: “Secure Disk Erase Failed-Couldn’t Unmount Disk.” This happens in a few circumstances, but most of the time because you’re trying to erase the entire disk-consult steps 5 and 6 above. Quit Disk Utility and use Reinstall macOS from the main recovery window.Select just the partition or container with macOS and click the Erase button.Fom the View menu, select Show All Devices. Make sure you’re selecting your macOS startup partition and not the entire drive, which contains the macOS Recovery partition you’re currently using.When Recovery starts up, select Disk Utility and click Continue.(If you see a globe, skip down to the end of the article.) Wait until the startup progress bar appears and release the keys.
Easy to follow tutorial on How To Run macOS Mojave from an external USB 3.0 SSD Drive. Detailed information and guidance on various aspects of current pharmacopoeial policy. When you’re trying to wipe an old Mac to set it up fresh or to give it away or sell it, you typically want to erase the drive.
