diff --git a/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/v1/validation/ValidationScriptRunner.java b/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/v1/validation/ValidationScriptRunner.java
index ff64c5dc1e89ab67d7b655d241afbcf0cb6c45f7..7375ca5c608bdec9cf9dee1bf4f45358b06e8675 100644
--- a/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/v1/validation/ValidationScriptRunner.java
+++ b/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/v1/validation/ValidationScriptRunner.java
@@ -110,7 +110,10 @@ public class ValidationScriptRunner
         ArrayList<ValidationError> errors = new ArrayList<ValidationError>();
         PyFunction function = tryJythonFunction(FILE_VALIDATION_FUNCTION_NAME);
         PyObject result = function.__call__(Py.java2py(dataSetFile));
-        errors.addAll((Collection<? extends ValidationError>) result);
+        if (null != result)
+        {
+            errors.addAll((Collection<? extends ValidationError>) result);
+        }
 
         return errors;
     }