Index: /trunk/src/VBox/ValidationKit/testmanager/batch/virtual_test_sheriff.py
===================================================================
--- /trunk/src/VBox/ValidationKit/testmanager/batch/virtual_test_sheriff.py	(revision 64942)
+++ /trunk/src/VBox/ValidationKit/testmanager/batch/virtual_test_sheriff.py	(revision 64943)
@@ -589,4 +589,6 @@
         Returns None if not found.
         """
+        if sHayStack is None:
+            return None;
         off = sHaystack.find(sNeedle);
         if off < 0: