diff --git a/src/main/java/org/olat/commons/coordinate/cluster/jms/ClusterEventBus.java b/src/main/java/org/olat/commons/coordinate/cluster/jms/ClusterEventBus.java
index 966f0c252e8d8de8a906a077efa111db9a362f6b..5e25c69922680368658da73456071a88792a7a9b 100644
--- a/src/main/java/org/olat/commons/coordinate/cluster/jms/ClusterEventBus.java
+++ b/src/main/java/org/olat/commons/coordinate/cluster/jms/ClusterEventBus.java
@@ -270,6 +270,7 @@ public class ClusterEventBus extends AbstractEventBus implements MessageListener
 				producer.send(message);
 			//TODO jms }
 		} catch (Exception e) {
+			log.error("Cannot send JMS message", e);
 			// cluster:::: what shall we do here: the JMS bus is broken! and we thus cannot know if other nodes are alive.
 			// if we are the only node running, then we could continue.
 			// a) either throw an exception - meaning olat doesn't really run at all and produces redscreens all the time and logging in is not possible.
diff --git a/src/main/java/org/olat/core/util/coordinate/LockEntry.java b/src/main/java/org/olat/core/util/coordinate/LockEntry.java
index d882adb11480cc723fbbe59385406da45cbd6d81..5eaa4bfa80f6da772776017c79bc1548b3eb21c3 100644
--- a/src/main/java/org/olat/core/util/coordinate/LockEntry.java
+++ b/src/main/java/org/olat/core/util/coordinate/LockEntry.java
@@ -25,6 +25,8 @@
 */ 
 package org.olat.core.util.coordinate;
 
+import java.io.Serializable;
+
 import org.olat.core.id.Identity;
 /**
  * Description: <br>
@@ -32,7 +34,10 @@ import org.olat.core.id.Identity;
  * 
  * @author Felix Jost
  */
-public class LockEntry {
+public class LockEntry implements Serializable {
+
+	private static final long serialVersionUID = -319510836505419325L;
+	
 	private long lockAquiredTime;
 	private Identity owner;
 	private final String key;