Index: branches/RC/core/kernel/db/dbitem.php
===================================================================
diff -u -r8929 -r9235
--- branches/RC/core/kernel/db/dbitem.php	(.../dbitem.php)	(revision 8929)
+++ branches/RC/core/kernel/db/dbitem.php	(.../dbitem.php)	(revision 9235)
@@ -573,7 +573,7 @@
 			foreach($unique_fields as $unique_field)
 			{
 				// if field is not empty or if it is required - we add where condition
-				if ($this->GetDBField($unique_field) != '' || $this->Fields[$unique_field]['required']) {
+				if ($this->GetDBField($unique_field) != '' || (isset($this->Fields[$unique_field]['required']) && $this->Fields[$unique_field]['required'])) {
 					$where[] = '`'.$unique_field.'` = '.$this->Conn->qstr( $this->GetDBField($unique_field) );
 				}
 			}