diff --git a/src/main/java/org/olat/core/commons/modules/bc/components/FolderComponent.java b/src/main/java/org/olat/core/commons/modules/bc/components/FolderComponent.java
index a8525046984244c248a7281cecd9226a83d71323..9f6f47d25bc01aaa77b8b84eedc5dff278b4598d 100644
--- a/src/main/java/org/olat/core/commons/modules/bc/components/FolderComponent.java
+++ b/src/main/java/org/olat/core/commons/modules/bc/components/FolderComponent.java
@@ -45,6 +45,8 @@ import org.olat.core.gui.components.ComponentRenderer;
 import org.olat.core.gui.control.Event;
 import org.olat.core.gui.translator.Translator;
 import org.olat.core.id.IdentityEnvironment;
+import org.olat.core.logging.OLog;
+import org.olat.core.logging.Tracing;
 import org.olat.core.logging.activity.CoreLoggingResourceable;
 import org.olat.core.logging.activity.ThreadLocalUserActivityLogger;
 import org.olat.core.util.Util;
@@ -60,6 +62,7 @@ import org.olat.core.util.vfs.version.Versionable;
  * @author Mike Stock
  */
 public class FolderComponent extends AbstractComponent {
+	private static final OLog log = Tracing.createLoggerFor(FolderComponent.class);
  	private static final ComponentRenderer RENDERER = new FolderComponentRenderer();
  	
 	public static final String SORT_NAME = "name";
@@ -350,19 +353,25 @@ public class FolderComponent extends AbstractComponent {
 		}
 
 		// get the children and sort them alphabetically
+		List<VFSItem> children;
 		if (filter != null) {
-			currentContainerChildren = currentContainer.getItems(filter);
+			children = currentContainer.getItems(filter);
 		} else {
-			currentContainerChildren = currentContainer.getItems();			
+			children = currentContainer.getItems();			
 		}
 		// OLAT-5256: filter .nfs files
-		Iterator<VFSItem> it = currentContainerChildren.iterator();
-		while(it.hasNext()) {
+		for(Iterator<VFSItem> it = children.iterator(); it.hasNext(); ) {
 			if (!exclFilter.accept(it.next())) {
 				it.remove();
 			}
 		}
-		Collections.sort(currentContainerChildren, comparator);
+		try {
+			Collections.sort(children, comparator);
+		} catch (Exception e) {
+			log.error("", e);
+		}
+		
+		currentContainerChildren = children;
 	}
 	
 	/**
diff --git a/src/main/java/org/olat/core/dispatcher/mapper/MapperDispatcher.java b/src/main/java/org/olat/core/dispatcher/mapper/MapperDispatcher.java
index 697795bf5ff84547b05ebf1e7fab19abe9ca38fd..ea66c08e10bc9eb74190bc3deaf17d25aea7de9f 100644
--- a/src/main/java/org/olat/core/dispatcher/mapper/MapperDispatcher.java
+++ b/src/main/java/org/olat/core/dispatcher/mapper/MapperDispatcher.java
@@ -68,16 +68,13 @@ public class MapperDispatcher extends LogDelegator implements Dispatcher {
 	 */
 	@Override
 	public void execute(HttpServletRequest hreq, HttpServletResponse hres) throws IOException {
+		if(!hreq.isRequestedSessionIdValid()) {
+			String pathInfo = hreq.getRequestURI();
+			DispatcherModule.sendForbidden(pathInfo, hres);
+			return;
+		}
 
 		String pathInfo = DispatcherModule.subtractContextPath(hreq);
-		final boolean isDebugLog = isLogDebugEnabled();
-		StringBuilder debugMsg = null;
-		long debug_start = 0;
-		if (isDebugLog) {
-			debug_start = System.currentTimeMillis();
-			debugMsg = new StringBuilder("::mprex:");
-		}
-		
 		// e.g. non-cacheable: 	23423/bla/blu.html
 		// e.g. cacheable: 		my.mapper.path/bla/blu.html
 		String subInfo = pathInfo.substring(DispatcherModule.PATH_MAPPED.length());
@@ -90,6 +87,7 @@ public class MapperDispatcher extends LogDelegator implements Dispatcher {
 			smappath = subInfo.substring(0, slashPos);
 		}
 		
+		
 		//legacy???
 		DBFactory.getInstance().commitAndCloseSession();
 
@@ -115,12 +113,5 @@ public class MapperDispatcher extends LogDelegator implements Dispatcher {
 		// /bla/blu.html
 		MediaResource mr = m.handle(mod, hreq);
 		ServletUtil.serveResource(hreq, hres, mr);
-
-		if (isDebugLog) {
-			long afterserved = System.currentTimeMillis();
-			long syncIntroDiff = afterserved - debug_start;
-			debugMsg.append("nanoseconds:").append(syncIntroDiff);
-			logDebug(debugMsg.toString());
-		}
 	}
 }
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