Index: units/sections/section_eh.php
===================================================================
--- units/sections/section_eh.php	(revision 13862)
+++ units/sections/section_eh.php	(working copy)
@@ -92,7 +92,7 @@
 			$grids['Default']['Fields'] = array_merge_recursive2($grids['Default']['Fields'], $new_columns);
 			$this->Application->setUnitOption($event->MasterEvent->Prefix, 'Grids', $grids);
 
-			if (!$this->Application->isAdmin) {
+			if (!$this->Application->isAdmin && is_object($this->Application->siteDomain)) {
 				// re-configure object, because it's recalled before kUnitConfigReader::AfterConfigRead is called
 				$this->Application->siteDomain->defineFields();
 			}