diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/dataaccess/db/ExternalDataDAO.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/dataaccess/db/ExternalDataDAO.java
index e69b0c26cb7c0d2f4c2463c04e707dab4e824383..9c488f1f11f45467b2db955d254967c32ec25507 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/dataaccess/db/ExternalDataDAO.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/dataaccess/db/ExternalDataDAO.java
@@ -175,7 +175,7 @@ final class ExternalDataDAO extends AbstractGenericEntityDAO<ExternalDataPE> imp
         if (operationLog.isDebugEnabled())
         {
             operationLog.debug(String.format(
-                    "%d external data have been found for [experiment=%e].", list.size(),
+                    "%d external data have been found for [experiment=%s].", list.size(),
                     experiment));
         }
         return list;