Index: lams_common/src/java/org/lamsfoundation/lams/web/controller/AbstractTimeLimitWebsocketServer.java
===================================================================
diff -u -r2bc8f0c2f65f02cb65aa7e90d0bbb612494a4588 -r307d08b374afefb264a041667fcbeaee2b58e44c
--- lams_common/src/java/org/lamsfoundation/lams/web/controller/AbstractTimeLimitWebsocketServer.java	(.../AbstractTimeLimitWebsocketServer.java)	(revision 2bc8f0c2f65f02cb65aa7e90d0bbb612494a4588)
+++ lams_common/src/java/org/lamsfoundation/lams/web/controller/AbstractTimeLimitWebsocketServer.java	(.../AbstractTimeLimitWebsocketServer.java)	(revision 307d08b374afefb264a041667fcbeaee2b58e44c)
@@ -1,41 +1,34 @@
 package org.lamsfoundation.lams.web.controller;
 
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.log4j.Logger;
+import org.lamsfoundation.lams.usermanagement.User;
+import org.lamsfoundation.lams.usermanagement.service.IUserManagementService;
+import org.lamsfoundation.lams.util.hibernate.HibernateSessionManager;
+import org.lamsfoundation.lams.web.session.SessionManager;
+import org.lamsfoundation.lams.web.util.AttributeNames;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.context.support.WebApplicationContextUtils;
+
+import javax.websocket.CloseReason;
+import javax.websocket.CloseReason.CloseCodes;
+import javax.websocket.OnClose;
+import javax.websocket.OnOpen;
+import javax.websocket.Session;
+import javax.websocket.server.ServerEndpointConfig;
 import java.io.IOException;
 import java.lang.reflect.Method;
 import java.time.Duration;
 import java.time.LocalDateTime;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.Map;
+import java.util.*;
 import java.util.Map.Entry;
-import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 
-import javax.websocket.CloseReason;
-import javax.websocket.CloseReason.CloseCodes;
-import javax.websocket.OnClose;
-import javax.websocket.OnOpen;
-import javax.websocket.Session;
-import javax.websocket.server.ServerEndpointConfig;
-
-import org.apache.log4j.Logger;
-import org.lamsfoundation.lams.usermanagement.User;
-import org.lamsfoundation.lams.usermanagement.service.IUserManagementService;
-import org.lamsfoundation.lams.util.hibernate.HibernateSessionManager;
-import org.lamsfoundation.lams.web.session.SessionManager;
-import org.lamsfoundation.lams.web.util.AttributeNames;
-import org.springframework.web.context.WebApplicationContext;
-import org.springframework.web.context.support.WebApplicationContextUtils;
-
-import com.fasterxml.jackson.databind.node.JsonNodeFactory;
-import com.fasterxml.jackson.databind.node.ObjectNode;
-
 /**
  * Controls activity time limits. Can be used in tools to set relative and absolute time limits for learners.
  *
@@ -109,7 +102,9 @@
 		// do nothing as server is probably shutting down and we could not obtain Hibernate session
 	    } catch (Exception e) {
 		// error caught, but carry on
-		log.error("Error in Assessment worker thread", e);
+		log.error("Error in time limit worker thread", e);
+		// extra details for debugging
+		e.printStackTrace();
 	    } finally {
 		HibernateSessionManager.closeSession();
 	    }
@@ -172,7 +167,7 @@
      */
     protected boolean processActivity(long toolContentId, Collection<Session> websockets) throws IOException {
 	// if all learners left the activity, remove the obsolete mapping
-	if (websockets.isEmpty()) {
+	if (websockets == null || websockets.isEmpty()) {
 	    timeCaches.remove(toolContentId);
 	    return false;
 	}
@@ -185,7 +180,8 @@
 	}
 
 	// get only currently active users, not all activity participants
-	Collection<Integer> userIds = websockets.stream().filter(w -> w.getUserProperties() != null)
+	Collection<Integer> userIds = websockets.stream()
+		.filter(w -> w.getUserProperties() != null && w.getUserProperties().get("userId") != null)
 		.collect(Collectors.mapping(w -> (Integer) w.getUserProperties().get("userId"), Collectors.toSet()));
 	// get activity data from DB
 	TimeCache existingTimeSettings = getExistingTimeSettings(toolContentId, userIds);
Index: lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/web/controller/LearningWebsocketServer.java
===================================================================
diff -u -r78cd74a85c22416138e9dd68dfb7e246c29b4c35 -r307d08b374afefb264a041667fcbeaee2b58e44c
--- lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/web/controller/LearningWebsocketServer.java	(.../LearningWebsocketServer.java)	(revision 78cd74a85c22416138e9dd68dfb7e246c29b4c35)
+++ lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/web/controller/LearningWebsocketServer.java	(.../LearningWebsocketServer.java)	(revision 307d08b374afefb264a041667fcbeaee2b58e44c)
@@ -52,8 +52,9 @@
 	    return existingTimeSettings;
 	}
 
-	existingTimeSettings.absoluteTimeLimit = assessment.getAbsoluteTimeLimit();
+	existingTimeSettings.absoluteTimeLimitFinish = assessment.getAbsoluteTimeLimitFinish();
 	existingTimeSettings.relativeTimeLimit = assessment.getRelativeTimeLimit() * 60;
+	existingTimeSettings.absoluteTimeLimit = assessment.getAbsoluteTimeLimit() * 60;
 	existingTimeSettings.timeLimitAdjustment = assessment.getTimeLimitAdjustments();
 
 	if (userIds != null) {
@@ -86,6 +87,9 @@
 	return assessmentService.launchTimeLimit(toolContentId, userId);
     }
 
+    /**
+     * Fetches or creates a singleton of this websocket server.
+     */
     public static LearningWebsocketServer getInstance() {
 	LearningWebsocketServer result = (LearningWebsocketServer) AbstractTimeLimitWebsocketServer.getInstance(
 		LearningWebsocketServer.class.getName());
@@ -96,9 +100,6 @@
 	return result;
     }
 
-    /**
-     * Fetches or creates a singleton of this websocket server.
-     */
     public static Long getSecondsLeft(long toolContentId, int userId) {
 	LearningWebsocketServer instance = LearningWebsocketServer.getInstance();
 	return AbstractTimeLimitWebsocketServer.getSecondsLeft(instance, toolContentId, userId, true);