Can't establish a websocket connection to a JavaEE Spring Server Application

i have a web application build up with spring mvc 4.1.3 on a Wildfly Server which has a websocket server implemented. About a few weeks ago everything worked as expected. Since then i didn't checked the websocket connection. Yesterday i wanted to check the features of the application and out of a sudden the websocket connection couldn't established. The Client, in my case chrome, reported the following error message

WebSocket connection to 'ws://127.0.0.1:8080/frontend/notificationws' failed: Error during WebSocket handshake: Unexpected response code: 200

Firefox reported the same error message, though the Server reported nothing. I tried to get any further information on the error message but had no luck yet. I observed the message exchange between the websocket server and client with wireshark but no luck either. Nothing suspicious found.

Websocket handling:

public class NotificationWs extends TextWebSocketHandler{
        @Override
        public void handleTextMessage(WebSocketSession session, TextMessage message) {
           logger.info("Payload: " + message.getPayload());
        }
}

Custom handshake:

public class NotificationHandshakeInterceptor extends HttpSessionHandshakeInterceptor {
    @Override
    public boolean beforeHandshake(ServerHttpRequest request,
            ServerHttpResponse response, WebSocketHandler wsHandler,
            Map<String, Object> attributes) throws Exception {
        logger.info("Before Handshake");
        return super.beforeHandshake(request, response, wsHandler, attributes);
    }

    @Override
    public void afterHandshake(ServerHttpRequest request,
            ServerHttpResponse response, WebSocketHandler wsHandler,
            Exception ex) {
        logger.info("After Handshake");
        super.afterHandshake(request, response, wsHandler, ex);

    }
}

Configuration in Servlet Context:

<bean id="notificationWs" class="com.supo.frontend.websocket.notification.NotificationWs" />
<websocket:handlers>
    <websocket:mapping path="/notificationws" handler="notificationWs"/>
    <websocket:handshake-interceptors>
        <bean class="com.supo.frontend.websocket.notification.NotificationHandshakeInterceptor"/>
    </websocket:handshake-interceptors>
</websocket:handlers>

javascript:

...
var uri = "ws://" + (document.location.hostname) + ":" + "8080" + "/frontend/notificationws";
websocket = new WebSocket(uri); 
...

I hope thats enough info. I would appreciate any help.