socket.io + cluster を使っていたら、クライアント側(HTML + JS)で以下のエラーが発生した。 WebSocket connection to 'ws://192.168.33.10:3000/socket.io/?EIO=3&transport=websocket&sid=nP02s_VbJ4I968puAAAO' failed: Connection closed before receiving a handshake response socket.io.js:2919 GET http://192.168.33.10:3000/socket.io/?EIO=3&transport=polling&t=1427000334124-80&sid=nP02s_VbJ4I968puAAAO 400 (Bad Request) socket.io.js:2919 P