Windows
Step One: Open Windows command prompt as Administrator
Step two: Find PID (ProcessID) for port 8080:
Command: netstat -aon | findstr 8080
Output Example: TCP 0.0.0.0:8080 0.0.0.0:0 LISTEN 77777
Step three: Kill the zombie process which is using that port:
Command: taskkill /f /pid <Number>
Example: taskkill /f /pid 77777
where "77777" is your PID
Close the command prompt and check the application.