diff --git a/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetFolderProcessor.java b/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetFolderProcessor.java
index 5de7a300775d729b319c9412c011537ff1f5efcc..39a2355e606f5234787c78010b1b348fab7c5a72 100644
--- a/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetFolderProcessor.java
+++ b/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetFolderProcessor.java
@@ -71,6 +71,7 @@ class SampleAndDataSetFolderProcessor extends AbstractSampleAndDataSetProcessor
                     controlFileProcessor.register();
                 } catch (UserFailureException e)
                 {
+                    e.printStackTrace();
                     errorMap.put(controlFile, e);
                 }
             }
diff --git a/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetRegistrationHandler.java b/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetRegistrationHandler.java
index 2020b85929b87c86b42a6165c3fd29be1bcf8df5..3fda03c513c14fbf7934b67ff3036fb086f157d7 100644
--- a/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetRegistrationHandler.java
+++ b/datastore_server/source/java/ch/systemsx/cisd/etlserver/entityregistration/SampleAndDataSetRegistrationHandler.java
@@ -145,6 +145,7 @@ public class SampleAndDataSetRegistrationHandler implements IDataSetHandlerWithM
             folderProcessor.register();
         } catch (Exception ex)
         {
+            ex.printStackTrace();
             operationLog.error("Could not register samples / data sets in ", ex);
             throw new CheckedExceptionTunnel(ex);
         } finally