What to do if your Mac’s hard drive starts unmounting itself unexpectedly

When you mount a drive in the Finder, you expect it to stay there. If you’ve found that your previously reliable external hard disk drive or SSD starts ejecting itself, trouble is obviously afoot. Apple
The message “Disk Not Ejected Properly” usually appears when you unplug a cable or disconnect power to a drive without making sure the disk has unmounted from the Finder after selecting it and choosing File > Eject [Name] or clicking the Eject icon next to its name in the sidebar.To read this article in full, please click here