Index: lams_common/src/java/org/lamsfoundation/lams/web/session/SystemSessionFilter.java
===================================================================
diff -u -rc7b64c1297f46800d132a6db434955b3a75ff34b -r4b9716d28667d58ca04bcef7da9e500248d7344d
--- lams_common/src/java/org/lamsfoundation/lams/web/session/SystemSessionFilter.java	(.../SystemSessionFilter.java)	(revision c7b64c1297f46800d132a6db434955b3a75ff34b)
+++ lams_common/src/java/org/lamsfoundation/lams/web/session/SystemSessionFilter.java	(.../SystemSessionFilter.java)	(revision 4b9716d28667d58ca04bcef7da9e500248d7344d)
@@ -23,7 +23,8 @@
 
 package org.lamsfoundation.lams.web.session;
 
-import java.io.IOException;
+import org.apache.log4j.Logger;
+import org.springframework.web.util.NestedServletException;
 
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
@@ -34,13 +35,11 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
+import java.io.IOException;
 
-import org.apache.log4j.Logger;
-import org.springframework.web.util.NestedServletException;
-
 /**
- * This filter must set before <code>org.lamsfoundation.lams.web.filter.LocaleFilter</code> in web.xml
- * because LocaleFilter need get value from SystemSession.
+ * This filter must set before <code>org.lamsfoundation.lams.web.filter.LocaleFilter</code> in web.xml because
+ * LocaleFilter need get value from SystemSession.
  *
  * @author Steve.Ni
  */
@@ -69,7 +68,7 @@
 	    chain.doFilter(request, response);
 	    return;
 	}
-	
+
 	HttpSession session = null;
 	try {
 	    session = SessionManager.startSession(httpRequest);
@@ -80,7 +79,7 @@
 		// There seems to be a problem with Infinispan session invalidation.
 		// Until we upgrade WildFly we need to keep these safety measures.
 		String sessionId = session.getId();
-		log.warn("Session " + sessionId + " was already invalidated");
+		log.warn("Session " + sessionId + " seems already invalidated: " + e.getCause().getMessage());
 		SessionManager.removeSessionByID(sessionId, false, true);
 	    } else {
 		throw e;
Index: lams_tool_doku/src/java/org/lamsfoundation/lams/tool/dokumaran/web/controller/LearningController.java
===================================================================
diff -u -rdbb83a20e36def6c8cb9763e542714cef162e0a2 -r4b9716d28667d58ca04bcef7da9e500248d7344d
--- lams_tool_doku/src/java/org/lamsfoundation/lams/tool/dokumaran/web/controller/LearningController.java	(.../LearningController.java)	(revision dbb83a20e36def6c8cb9763e542714cef162e0a2)
+++ lams_tool_doku/src/java/org/lamsfoundation/lams/tool/dokumaran/web/controller/LearningController.java	(.../LearningController.java)	(revision 4b9716d28667d58ca04bcef7da9e500248d7344d)
@@ -292,7 +292,6 @@
 	ObjectNode responseJSON = JsonNodeFactory.instance.objectNode();
 	responseJSON.put(DokumaranConstants.ATTR_IS_LEADER_RESPONSE_FINALIZED, isLeaderResponseFinalized);
 	response.setContentType("application/json;charset=utf-8");
-	response.getWriter().print(responseJSON);
 	return responseJSON.toString();
     }
 
Index: lams_tool_doku/web/pages/learning/learning.jsp
===================================================================
diff -u -r876e644c066e81c2721ffa085fd12f386e2f3bb6 -r4b9716d28667d58ca04bcef7da9e500248d7344d
--- lams_tool_doku/web/pages/learning/learning.jsp	(.../learning.jsp)	(revision 876e644c066e81c2721ffa085fd12f386e2f3bb6)
+++ lams_tool_doku/web/pages/learning/learning.jsp	(.../learning.jsp)	(revision 4b9716d28667d58ca04bcef7da9e500248d7344d)
@@ -73,38 +73,38 @@
 
 				let timeLimitExceeded = ${timeLimitExceeded};
 				initWebsocket('dokuTimeLimit${sessionMap.toolContentID}',
-								'<lams:WebAppURL />'.replace('http', 'ws')
-								+ 'learningWebsocket?toolContentID=${sessionMap.toolContentID}',
-								function (e) {
-									// create JSON object
-									var input = JSON.parse(e.data);
+						'<lams:WebAppURL />'.replace('http', 'ws')
+						+ 'learningWebsocket?toolContentID=${sessionMap.toolContentID}',
+						function (e) {
+							// create JSON object
+							var input = JSON.parse(e.data);
 
-									if (input.clearTimer == true) {
-										// teacher stopped the timer, destroy it
-										$('#countdown').countdown('destroy').remove();
-									} else if (typeof input.secondsLeft != 'undefined'){
-										// teacher updated the timer
-										var secondsLeft = +input.secondsLeft,
-												counterInitialised = $('#countdown').length > 0;
+							if (input.clearTimer == true) {
+								// teacher stopped the timer, destroy it
+								$('#countdown').countdown('destroy').remove();
+							} else if (typeof input.secondsLeft != 'undefined'){
+								// teacher updated the timer
+								var secondsLeft = +input.secondsLeft,
+										counterInitialised = $('#countdown').length > 0;
 
-										if (counterInitialised) {
-											// just set the new time
-											$('#countdown').countdown('option', 'until', secondsLeft + 'S');
-										} else if (timeLimitExceeded){
-											if (secondsLeft > 0) {
-												// teacher gave extra time, reload to writable Etherpad
-												location.reload();
-												return;
-											}
-										} else {
-											// initialise the timer
-											displayCountdown(secondsLeft);
-										}
+								if (counterInitialised) {
+									// just set the new time
+									$('#countdown').countdown('option', 'until', secondsLeft + 'S');
+								} else if (timeLimitExceeded){
+									if (secondsLeft > 0) {
+										// teacher gave extra time, reload to writable Etherpad
+										location.reload();
+										return;
 									}
+								} else {
+									// initialise the timer
+									displayCountdown(secondsLeft);
+								}
+							}
 
-									// reset ping timer
-									websocketPing('dokuTimeLimit${sessionMap.toolContentID}', true);
-								});
+							// reset ping timer
+							websocketPing('dokuTimeLimit${sessionMap.toolContentID}', true);
+						});
 
 				$('[data-toggle="tooltip"]').bootstrapTooltip();
 			});
@@ -286,12 +286,12 @@
 							<fmt:message key="label.continue" />
 						</button>
 					</c:when>
-					<c:when test="${!hasEditRight && !sessionMap.userFinished && !sessionMap.isLeaderResponseFinalized}">
-						<%-- show no button for non-leaders until leader will finish activity  --%>
-					</c:when>
 					<c:otherwise>
 						<a href="#nogo" name="FinishButton" id="finish-button"
-						   class="btn btn-primary voffset5 pull-right na">
+						   class="btn btn-primary voffset5 pull-right na"
+								<c:if test="${!hasEditRight && !sessionMap.userFinished && !sessionMap.isLeaderResponseFinalized}">
+									style="display: none"
+								</c:if>>
 							<span class="nextActivity">
 								<c:choose>
 									<c:when test="${sessionMap.isLastActivity}">
Index: lams_tool_whiteboard/src/java/org/lamsfoundation/lams/tool/whiteboard/web/controller/LearningController.java
===================================================================
diff -u -r1621b6daf8385b83e75f7ffde03c017b05c12487 -r4b9716d28667d58ca04bcef7da9e500248d7344d
--- lams_tool_whiteboard/src/java/org/lamsfoundation/lams/tool/whiteboard/web/controller/LearningController.java	(.../LearningController.java)	(revision 1621b6daf8385b83e75f7ffde03c017b05c12487)
+++ lams_tool_whiteboard/src/java/org/lamsfoundation/lams/tool/whiteboard/web/controller/LearningController.java	(.../LearningController.java)	(revision 4b9716d28667d58ca04bcef7da9e500248d7344d)
@@ -23,19 +23,8 @@
 
 package org.lamsfoundation.lams.tool.whiteboard.web.controller;
 
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Date;
-import java.util.List;
-import java.util.Set;
-import java.util.TimeZone;
-
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
-import javax.servlet.http.HttpSession;
-
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
 import org.apache.log4j.Logger;
 import org.lamsfoundation.lams.notebook.model.NotebookEntry;
 import org.lamsfoundation.lams.notebook.service.CoreNotebookConstants;
@@ -62,8 +51,17 @@
 import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.bind.annotation.RequestMapping;
 
-import com.fasterxml.jackson.databind.node.JsonNodeFactory;
-import com.fasterxml.jackson.databind.node.ObjectNode;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpSession;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Date;
+import java.util.List;
+import java.util.Set;
+import java.util.TimeZone;
 
 @Controller
 @RequestMapping("/learning")
@@ -273,7 +271,6 @@
 	ObjectNode responseJSON = JsonNodeFactory.instance.objectNode();
 	responseJSON.put(WhiteboardConstants.ATTR_IS_LEADER_RESPONSE_FINALIZED, isLeaderResponseFinalized);
 	response.setContentType("application/json;charset=utf-8");
-	response.getWriter().print(responseJSON);
 	return responseJSON.toString();
     }
 
@@ -394,4 +391,4 @@
 	}
 	return whiteboardUser;
     }
-}
+}
\ No newline at end of file
Index: lams_tool_whiteboard/web/pages/learning/learning.jsp
===================================================================
diff -u -r876e644c066e81c2721ffa085fd12f386e2f3bb6 -r4b9716d28667d58ca04bcef7da9e500248d7344d
--- lams_tool_whiteboard/web/pages/learning/learning.jsp	(.../learning.jsp)	(revision 876e644c066e81c2721ffa085fd12f386e2f3bb6)
+++ lams_tool_whiteboard/web/pages/learning/learning.jsp	(.../learning.jsp)	(revision 4b9716d28667d58ca04bcef7da9e500248d7344d)
@@ -318,7 +318,10 @@
 					</c:when>
 					<c:otherwise>
 						<a href="#nogo" name="FinishButton" id="finish-button"
-						   class="btn btn-primary voffset5 pull-right na">
+						   class="btn btn-primary voffset5 pull-right na"
+								<c:if test="${!hasEditRight && !sessionMap.userFinished && !sessionMap.isLeaderResponseFinalized}">
+									style="display: none"
+								</c:if>>
 							<span class="nextActivity">
 								<c:choose>
 									<c:when test="${sessionMap.isLastActivity}">