diff --git a/src/main/java/org/olat/core/commons/services/video/MovieServiceImpl.java b/src/main/java/org/olat/core/commons/services/video/MovieServiceImpl.java
index e8024ba27dd5af7a598c7b6509c5bca87c3a5cda..b30f5e84e7970cc9b65dc38dd834b0468e66d79c 100644
--- a/src/main/java/org/olat/core/commons/services/video/MovieServiceImpl.java
+++ b/src/main/java/org/olat/core/commons/services/video/MovieServiceImpl.java
@@ -125,7 +125,8 @@ public class MovieServiceImpl implements MovieService, ThumbnailSPI {
 					size = new FinalSize(scaledSize.getWidth(), scaledSize.getHeight());
 				}
 			//NullPointerException can be thrown if the jcodec cannot handle the codec of the movie
-			} catch (IOException | JCodecException | NullPointerException e) {
+			//ArrayIndexOutOfBoundsException 
+			} catch (Exception e) {
 				log.error("", e);
 			}
 		}
diff --git a/src/main/java/org/olat/core/gui/components/form/flexible/impl/elements/MultipleSelectionElementImpl.java b/src/main/java/org/olat/core/gui/components/form/flexible/impl/elements/MultipleSelectionElementImpl.java
index 6ad36c8e02bad989204d48d069655fc24f400977..cf7064c65d9043cb28c301c5fe62af36cd17310a 100644
--- a/src/main/java/org/olat/core/gui/components/form/flexible/impl/elements/MultipleSelectionElementImpl.java
+++ b/src/main/java/org/olat/core/gui/components/form/flexible/impl/elements/MultipleSelectionElementImpl.java
@@ -347,10 +347,14 @@ public class MultipleSelectionElementImpl extends FormItemImpl implements Multip
 		}
 		
 		// create and add selectbox element
-		String ssscId = getFormItemId() == null ? null : getFormItemId() + "_SELBOX";
-		component = new MultipleSelectionComponent(ssscId, this);
-		component.setDomReplacementWrapperRequired(domReplacementWrapperRequired);
-		component.setCheckComponents(ssecs);
+		if(component == null) {
+			String ssscId = getFormItemId() == null ? null : getFormItemId() + "_SELBOX";
+			component = new MultipleSelectionComponent(ssscId, this);
+			component.setDomReplacementWrapperRequired(domReplacementWrapperRequired);
+			component.setCheckComponents(ssecs);
+		} else {
+			component.setCheckComponents(ssecs);
+		}
 	}
 
 	/**
diff --git a/src/main/java/org/olat/course/editor/EditorMainController.java b/src/main/java/org/olat/course/editor/EditorMainController.java
index 579da614da9587a82a1a36c933d4701934b40425..e35618819ea82dc462708acb131275689e3dbd1a 100644
--- a/src/main/java/org/olat/course/editor/EditorMainController.java
+++ b/src/main/java/org/olat/course/editor/EditorMainController.java
@@ -649,10 +649,7 @@ public class EditorMainController extends MainLayoutBasicController implements G
 			}
 			
 			//aggressive clean-up
-			removeAsListenerAndDispose(moveCopyController);
-			removeAsListenerAndDispose(cmc);
-			moveCopyController = null;
-			cmc = null;
+			cleanUp();
 		} else if (source == insertNodeController) {     			
 			cmc.deactivate();
 			if (event == Event.DONE_EVENT) {
@@ -733,6 +730,8 @@ public class EditorMainController extends MainLayoutBasicController implements G
 	}
 	
 	private void doMove(UserRequest ureq, ICourse course, boolean copy) {
+		if(moveCopyController != null) return;
+		
 		TreeNode tn = menuTree.getSelectedNode();
 		if (tn == null) {
 			showError(NLS_MOVECOPYNODE_ERROR_SELECTFIRST);
diff --git a/src/main/java/org/olat/course/run/navigation/NavigationHandler.java b/src/main/java/org/olat/course/run/navigation/NavigationHandler.java
index d22a948cc8ef63fcfe4a9e598218d5a4ab4949d3..5c827789e4e2ea32da4c9960acd057d8ceb471d8 100644
--- a/src/main/java/org/olat/course/run/navigation/NavigationHandler.java
+++ b/src/main/java/org/olat/course/run/navigation/NavigationHandler.java
@@ -143,7 +143,7 @@ public class NavigationHandler implements Disposable {
 		String treeNodeId = treeEvent.getNodeId();
 		TreeNode selTN = treeModel.getNodeById(treeNodeId);
 		if (selTN == null) {
-			throw new AssertException("no treenode found:" + treeNodeId);
+			selTN = treeModel.getRootNode();
 		}
 
 		// check if appropriate for subtreemodelhandler
diff --git a/src/main/java/org/olat/repository/_i18n/LocalStrings_de.properties b/src/main/java/org/olat/repository/_i18n/LocalStrings_de.properties
index 713ba6e8d45533b5b90d90237b5565f6b6b1115f..3ab0efb395ef44668694259c630bb14b981841a4 100644
--- a/src/main/java/org/olat/repository/_i18n/LocalStrings_de.properties
+++ b/src/main/java/org/olat/repository/_i18n/LocalStrings_de.properties
@@ -502,7 +502,7 @@ start=starten
 start.with.type={0} starten
 status.closed=Beendet (Geschlossen)
 status.opened=Aktiv (Offen)
-tab.accesscontrol=Zugangskontrolle
+tab.accesscontrol=Zugangskonfiguration
 tab.calendar=Kalender
 tab.chat=Kurs-Chat
 tab.efficencystatement=Leistungsnachweis