How do I resolve the 'connection refused' error?

​Connection refused error occurs when the server is not running properly. For example, when the server itself has not been executed or if the process has died due to an error of the server.
First, check if the server is running properly, because the port setting can be a problem. Make sure that the port in the project URL is the same port that the server is running.
"Run" button
You can find the port number of the project URL in [Project] > [Running URL and Port] on the upper menu of IDE.
If the problem still occurs, please check the application is listening on (Set host of the server application as and restart the server).