From an elevated prompt run [ps]netstat -aon | findstr :9990[/ps] That will give you the offending PID: [ps]TCP 127.0.0.1:9990 0.0.0.0:0 LISTENING 1776[/ps] Quick check in Windows Task Manager will give you the process that is currently using the port so you can shut it down from there if need be. Read more →