Ender 3 will not connect

I cannot get Octoprint to connect to my Ender 3. I have used Auto and manual mode to connect with baud rates. I can connect with the same cable using Astroprint. This is the error messages I get. Can someone please help? Thanks

Changing monitoring state from "Offline" to "Error: Connection error, see Terminal tab"
Unexpected error while connecting to serial port: AUTO IOError: 'GPX plugin not able to discover AUTO port and/or baudrate. Please choose specific values for them.' @ comm.py:_openSerial:2478 (hook GPX)
Changing monitoring state from "Offline" to "Error: Connection error, see Terminal tab"
Unexpected error while connecting to serial port: AUTO IOError: 'GPX plugin not able to discover AUTO port and/or baudrate. Please choose specific values for them.' @ comm.py:_openSerial:2478 (hook GPX)

Why do you have the GPX plugin installed? You certainly shouldn't need that for the Ender 3.

Also it doesn't appear to like AUTO port or baudrate, so instead of leaving those at AUTO select one of the options offered to you in the dropdown.