diff --git a/kubernetes-kit-starter/src/main/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializer.java b/kubernetes-kit-starter/src/main/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializer.java
index 5faa872..5c2591f 100644
--- a/kubernetes-kit-starter/src/main/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializer.java
+++ b/kubernetes-kit-starter/src/main/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializer.java
@@ -279,7 +279,9 @@ private void queueSerialization(String sessionId,
                                 sessionId, clusterKey, error);
                     } else {
                         Consumer<SessionInfo> whenSerialized = sessionInfo -> {
-                            backendConnector.sendSession(sessionInfo);
+                            if (sessionInfo != null) {
+                                backendConnector.sendSession(sessionInfo);
+                            }
                             backendConnector
                                     .markSerializationComplete(clusterKey);
                         };
diff --git a/kubernetes-kit-starter/src/test/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializerTest.java b/kubernetes-kit-starter/src/test/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializerTest.java
index a48038d..4b13b95 100644
--- a/kubernetes-kit-starter/src/test/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializerTest.java
+++ b/kubernetes-kit-starter/src/test/java/com/vaadin/kubernetes/starter/sessiontracker/SessionSerializerTest.java
@@ -291,7 +291,8 @@ void serialize_notSerializableException_notFallbackToPessimistic() {
         verify(connector).markSerializationStarted(clusterSID);
 
         await().atMost(500, MILLISECONDS).untilTrue(serializationCompleted);
-        verify(connector).sendSession(isNull());
+        verify(connector, never()).sendSession(any());
+        verify(connector).markSerializationComplete(clusterSID);
         locks.forEach(l -> verify(l, never()).lock());
 
     }