Qt application running with `-platform offscreen` argument cannot establish websocket connection
Qt application running with `-platform offscreen` argument cannot establish websocket connection I have a GUI application which contains a websocket server QWebSocketServer . I also have a python script which sends messages and the application processes them. Everything works well. During testing I wanted to run the application in headless mode using -platform offscreen command line argument added to the app executable name (I changed nothing else). But the problem is that when the application runs off-screen, the client script cannot establish connection with the web socket server. I tested this on localhost only. I do not understand how this two things, visibility of GUI and websockets, can interfere. Any ideas what could go wrong? QWebSocketServer -platform offscreen Note: I am using Qt 5.11.1 64-bit with VS 2017 on Windows 10 Pro. I further exploring the issue. I tried the same with another application and it seems to work well even for -platform offscr...