This error was encountered upon attempting to refresh a DNN development website. 

image

In this particular case I following the steps below to resolve:

  1. Open a command prompt
  2. execute the following command: netstat –ano
  3. Locate the PID LISTENING on port 80
    1. In my case this was 1620 (see below)
    2. image
  4. Open Task Manager
  5. Switch to the Services tab and locate the service with the identified PID
    1. in my case this was an FTP utility
  6. Stop the associated service and/or kill the task
  7. Attempt to start the website: At this point I was able to successfully start my website.

Thanks for reading!

-Dan