Index: lams_tool_chat/src/java/org/lamsfoundation/lams/tool/chat/web/actions/LearningWebsocketServer.java
===================================================================
diff -u -r5773f84ed608838de3521ecde87c52f3c72d478c -r2587f45a620c6f3a3bbdc75111954853deb1ccf3
--- lams_tool_chat/src/java/org/lamsfoundation/lams/tool/chat/web/actions/LearningWebsocketServer.java	(.../LearningWebsocketServer.java)	(revision 5773f84ed608838de3521ecde87c52f3c72d478c)
+++ lams_tool_chat/src/java/org/lamsfoundation/lams/tool/chat/web/actions/LearningWebsocketServer.java	(.../LearningWebsocketServer.java)	(revision 2587f45a620c6f3a3bbdc75111954853deb1ccf3)
@@ -159,7 +159,9 @@
 			responseJSON.put("roster", rosterJSON);
 
 			// send the payload to the Learner's browser
-			websocket.session.getBasicRemote().sendText(responseJSON.toString());
+			if (websocket.session.isOpen()) {
+			    websocket.session.getBasicRemote().sendText(responseJSON.toString());
+			}
 		    }
 		} catch (Exception e) {
 		    LearningWebsocketServer.log.error("Error while building message JSON", e);