How do I fix a “The disk was not ejected properly” error?

Mac only.

You're trying to scan while Doxie One is connected to your computer.

Doxie is a standalone document scanner, designed to be used while disconnected from your computer. Doxie can't write to its memory if your computer is also accessing it. Like a digital camera, Doxie works while disconnected -- you scan, then download at some later point in time.

So, don't scan while connected to your computer. If you do so, your computer thinks you're continuously unplugging and reconnecting the scanner.