CherryPy Hello World error

If you are trying to deploy CherryPy on Heroku, where you cannot use the loopback to check whether you have really opened a port, then you need to simply disable CherryPy's wait_for_occupied_port() function so that CherryPy's self-consistency check does not decide that it has, in fact, failed to start. Here are the three lines that I use to fix CherryPy so that it runs on Heroku:

    from cherrypy.process import servers
    def fake_wait_for_occupied_port(host, port): return
    servers.wait_for_occupied_port = fake_wait_for_occupied_port

You've probably got something else listening on that port.

On Linux do:

netstat -pnl | grep 8080

And see what process is listening on 8080

On Windows use something like TCPView to do the same.