diff --git a/full/src/main/java/de/ids_mannheim/de/init/VCLoaderImpl.java b/full/src/main/java/de/ids_mannheim/de/init/VCLoaderImpl.java
new file mode 100644
index 0000000..113a6cc
--- /dev/null
+++ b/full/src/main/java/de/ids_mannheim/de/init/VCLoaderImpl.java
@@ -0,0 +1,19 @@
+package de.ids_mannheim.de.init;
+
+import org.springframework.beans.factory.annotation.Autowired;
+
+import de.ids_mannheim.korap.KrillCollection;
+import de.ids_mannheim.korap.config.NamedVCLoader;
+
+public class VCLoaderImpl implements VCLoader{
+
+    @Autowired
+    private NamedVCLoader vcLoader;
+    
+    @Override
+    public void recachePredefinedVC () {
+        KrillCollection.cache.removeAll();
+        Thread t = new Thread(vcLoader);
+        t.start();
+    }
+}
diff --git a/full/src/main/java/de/ids_mannheim/korap/config/NamedVCLoader.java b/full/src/main/java/de/ids_mannheim/korap/config/NamedVCLoader.java
index de7ac08..014a057 100644
--- a/full/src/main/java/de/ids_mannheim/korap/config/NamedVCLoader.java
+++ b/full/src/main/java/de/ids_mannheim/korap/config/NamedVCLoader.java
@@ -98,6 +98,7 @@
                 }
                 catch (KustvaktException e) {
                     // ignore
+                    if (DEBUG) jlog.debug(e);
                 }
                 vcService.storeVC(filename, VirtualCorpusType.SYSTEM, json,
                         null, null, null, true, "system");
diff --git a/full/src/main/java/de/ids_mannheim/korap/service/VirtualCorpusService.java b/full/src/main/java/de/ids_mannheim/korap/service/VirtualCorpusService.java
index 187b738..6b530bc 100644
--- a/full/src/main/java/de/ids_mannheim/korap/service/VirtualCorpusService.java
+++ b/full/src/main/java/de/ids_mannheim/korap/service/VirtualCorpusService.java
@@ -15,6 +15,7 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 
+import de.ids_mannheim.korap.KrillCollection;
 import de.ids_mannheim.korap.config.FullConfiguration;
 import de.ids_mannheim.korap.constant.GroupMemberStatus;
 import de.ids_mannheim.korap.constant.VirtualCorpusAccessStatus;
@@ -213,6 +214,9 @@
                 userGroupService.deleteAutoHiddenGroup(
                         access.getUserGroup().getId(), "system");
             }
+            if (KrillCollection.cache.get(vc.getName())!=null){
+                KrillCollection.cache.remove(vc.getName());
+            }
             vcDao.deleteVirtualCorpus(vc);
         }
         else {
diff --git a/full/src/main/java/de/ids_mannheim/korap/web/controller/AuthenticationController.java b/full/src/main/java/de/ids_mannheim/korap/web/controller/AuthenticationController.java
index b3594fd..bca7dc2 100644
--- a/full/src/main/java/de/ids_mannheim/korap/web/controller/AuthenticationController.java
+++ b/full/src/main/java/de/ids_mannheim/korap/web/controller/AuthenticationController.java
@@ -58,15 +58,16 @@
  * @date 24/01/2014
  * 
  * @author margaretha
- * @last-update 28/08/2018
+ * @last-update 01/07/2019
  * 
  * - added user authentication time in token context
  * - added api version filter
+ * - changed the response media-type 
  */
 @Controller
 @Path("/{version}/auth")
 @ResourceFilters({APIVersionFilter.class, PiwikFilter.class })
-@Produces(MediaType.TEXT_HTML + ";charset=utf-8")
+@Produces(MediaType.APPLICATION_JSON + ";charset=utf-8")
 public class AuthenticationController {
 
     @Autowired
diff --git a/full/src/main/java/de/ids_mannheim/korap/web/controller/VirtualCorpusController.java b/full/src/main/java/de/ids_mannheim/korap/web/controller/VirtualCorpusController.java
index 60beaea..87a98c8 100644
--- a/full/src/main/java/de/ids_mannheim/korap/web/controller/VirtualCorpusController.java
+++ b/full/src/main/java/de/ids_mannheim/korap/web/controller/VirtualCorpusController.java
@@ -33,6 +33,7 @@
 import de.ids_mannheim.korap.web.filter.APIVersionFilter;
 import de.ids_mannheim.korap.web.filter.AuthenticationFilter;
 import de.ids_mannheim.korap.web.filter.BlockingFilter;
+import de.ids_mannheim.korap.web.filter.DemoUserFilter;
 import de.ids_mannheim.korap.web.filter.PiwikFilter;
 import de.ids_mannheim.korap.web.input.VirtualCorpusJson;
 
@@ -115,6 +116,8 @@
     @GET
     @Path("{createdBy}/{vcName}")
     @Produces(MediaType.APPLICATION_JSON + ";charset=utf-8")
+    @ResourceFilters({ APIVersionFilter.class, AuthenticationFilter.class,
+        DemoUserFilter.class, PiwikFilter.class })
     public VirtualCorpusDto retrieveVCByName (
             @Context SecurityContext securityContext,
             @PathParam("createdBy") String createdBy,
diff --git a/full/src/main/resources/default-config.xml b/full/src/main/resources/default-config.xml
index a3de4ac..bd25718 100644
--- a/full/src/main/resources/default-config.xml
+++ b/full/src/main/resources/default-config.xml
@@ -193,7 +193,9 @@
 	<bean id="initializator" class="de.ids_mannheim.de.init.InitializatorImpl"
 		init-method="initAnnotation">
 	</bean>
-
+	
+	<bean id="vcLoader" class="de.ids_mannheim.de.init.VCLoaderImpl"/>
+	
 	<!-- Krill -->
 	<bean id="search_krill" class="de.ids_mannheim.korap.web.SearchKrill">
 		<constructor-arg value="${krill.indexDir}" />