Index: lams_learning/src/java/org/lamsfoundation/lams/learning/presence/PresenceWebsocketServer.java
===================================================================
diff -u -r5773f84ed608838de3521ecde87c52f3c72d478c -r2a758eb606c45d54e02a9d7f9597ce4aeb836e05
--- lams_learning/src/java/org/lamsfoundation/lams/learning/presence/PresenceWebsocketServer.java	(.../PresenceWebsocketServer.java)	(revision 5773f84ed608838de3521ecde87c52f3c72d478c)
+++ lams_learning/src/java/org/lamsfoundation/lams/learning/presence/PresenceWebsocketServer.java	(.../PresenceWebsocketServer.java)	(revision 2a758eb606c45d54e02a9d7f9597ce4aeb836e05)
@@ -146,7 +146,9 @@
 		    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) {
 		    PresenceWebsocketServer.log.error("Error while building message JSON", e);
 		}