This error was encountered upon attempting to refresh a DNN development website.
In this particular case I following the steps below to resolve:
- Open a command prompt
- execute the following command: netstat –ano
- Locate the PID LISTENING on port 80
- Open Task Manager
- Switch to the Services tab and locate the service with the identified PID
- in my case this was an FTP utility
- Stop the associated service and/or kill the task
- Attempt to start the website: At this point I was able to successfully start my website.
Thanks for reading!