Index: lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/LearningWebsocketServer.java
===================================================================
RCS file: /usr/local/cvsroot/lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/Attic/LearningWebsocketServer.java,v
diff -u -r1.1.2.1 -r1.1.2.2
--- lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/LearningWebsocketServer.java	14 Apr 2016 12:19:52 -0000	1.1.2.1
+++ lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/LearningWebsocketServer.java	22 Apr 2016 18:31:15 -0000	1.1.2.2
@@ -217,8 +217,12 @@
 	responseJSON.put("close", true);
 	String response = responseJSON.toString();
 
+	Set<Session> sessionWebsockets = LearningWebsocketServer.websockets.get(toolSessionId);
+	if (sessionWebsockets == null) {
+	    return;
+	}
 	// make a copy of the websocket collection so it does not get blocked while sending messages
-	Set<Session> sessionWebsockets = new HashSet<Session>(LearningWebsocketServer.websockets.get(toolSessionId));
+	sessionWebsockets = new HashSet<Session>(sessionWebsockets);
 	for (Session websocket : sessionWebsockets) {
 	    websocket.getBasicRemote().sendText(response);
 	}