System.Net.Sockets.SocketException: 'Only one usage of each socket address (protocol/network address/port) is normally

 System.Net.Sockets.SocketException: 'Only one usage of each socket address (protocol/network address/port) is normally

Option 1

1. Open the Command Prompt.
2. Type netstat -ano | findstr ":80" - where "80" is the port number you are searching for.
3. Look at the last column in the results - the PID.
4. For each PID running that you want to kill, execute taskkill /PID <PID> /F in the Command Prompt window (where <PID> is the PID that needs to be killed).

Option 2

If Option 1 above doesn't work, try rebooting your machine.