diff --git a/src/main/java/org/olat/instantMessaging/ui/InstantMessagingMainController.java b/src/main/java/org/olat/instantMessaging/ui/InstantMessagingMainController.java
index 491f4e29dd56f1e12835e1faa0fdfd4a81419dcb..fc880fb477ef2b9365564a8fa9d75ce590fe9d8f 100644
--- a/src/main/java/org/olat/instantMessaging/ui/InstantMessagingMainController.java
+++ b/src/main/java/org/olat/instantMessaging/ui/InstantMessagingMainController.java
@@ -336,7 +336,9 @@ public class InstantMessagingMainController extends BasicController implements G
 			inAssessment = true;
 			main.contextPut("inAssessment", true);
 			chatMgrCtrl.closeAllChats();
-			rosterPanelCtr.executeCloseCommand();
+			if(rosterPanelCtr != null) {
+				rosterPanelCtr.executeCloseCommand();
+			}
 		} else if(event.getEventType().equals(AssessmentEvent.TYPE.STOPPED)) {
 			OLATResourceable a = OresHelper.createOLATResourceableType(AssessmentInstance.class);
 			if (singleUserEventCenter.getListeningIdentityCntFor(a) < 1) {