How Do You Get the Docker Service to Start when You Get “Failed to start Docker Application Container Engine”?

Problem scenario
"Failed to start Docker Application Container Engine"

Possible solution
Run this:

sudo systemctl status docker.service

Examine the output. Does the "Drop-In" section include an override.conf file or other wise refer to a .conf file?

Back up the file (e.g., to your home directory).
Remove the original file.
Then run these commands:

sudo systemctl daemon-reload
sudo systemctl start docker