This article provides instructions to prevent random ejection of external drives on Mac.
The message “Disk Not Ejected Properly” usually appears when an external drive is disconnected from the computer without safely ejecting. However, some users have reported issues with drives randomly ejecting themselves after updating the macOS. Most reports indicate that the issue is seen after the computer has gone to sleep. See the prompt below:
There are a few other instances that can cause random ejection of an external drive:
The best method to avoid unexpected ejections is safely ejecting the drive when you are done using it. Use one of the methods listed below to eject an external drive:
If your drive was working normally and the ejection issue started after upgrading the macOS, the issue may relate to macOS itself. If that’s the case, a method that prevents both computer and external drive from sleeping avoids unexpected ejection. See the steps below:
Note: The workaround will not work if the Mac is operating on battery. The Mac power supply must remain connected and the computer lid must remain open.
Note: Your drive may still eject if you manually put your Mac to sleep even after changing these settings. In this case, it’s best to safely eject your drive before you put the Mac to sleep.