Index: branches/RC/core/units/custom_data/custom_data_event_handler.php
===================================================================
diff -u -r10492 -r10832
--- branches/RC/core/units/custom_data/custom_data_event_handler.php	(.../custom_data_event_handler.php)	(revision 10492)
+++ branches/RC/core/units/custom_data/custom_data_event_handler.php	(.../custom_data_event_handler.php)	(revision 10832)
@@ -69,6 +69,9 @@
 		function OnAfterConfigRead(&$event)
 		{
 			$main_prefix = $this->Application->getUnitOption($event->Prefix, 'ParentPrefix');
+			if (!$main_prefix) {
+				return false;
+			}
 
 			$custom_fields = $this->scanCustomFields($main_prefix);
 			if (!$custom_fields) {