Unable to program Arduino mega2560?
Com 20 is not configured with your arduino. Go to the arduino program and I think it is on the tools tab or the one next to it. There should be a port label and it says which com port to use. Then go to device manager, then ports. Then go to properties on the port that has arduino and change that to the port the arduino program said. It should work then. This topic has been solved many times.