diff --git a/eZ/Publish/Core/Persistence/Legacy/Content/Search/Gateway/CriteriaConverter.php b/eZ/Publish/Core/Persistence/Legacy/Content/Search/Gateway/CriteriaConverter.php
index <HASH>..<HASH> 100644
--- a/eZ/Publish/Core/Persistence/Legacy/Content/Search/Gateway/CriteriaConverter.php
+++ b/eZ/Publish/Core/Persistence/Legacy/Content/Search/Gateway/CriteriaConverter.php
@@ -10,8 +10,8 @@
 namespace eZ\Publish\Core\Persistence\Legacy\Content\Search\Gateway;
 
 use eZ\Publish\API\Repository\Values\Content\Query\Criterion;
+use eZ\Publish\API\Repository\Exceptions\NotImplementedException;
 use ezcQuerySelect;
-use RuntimeException;
 
 /**
  * Content locator gateway implementation using the zeta database component.
@@ -57,6 +57,6 @@ class CriteriaConverter
             }
         }
 
-        throw new RuntimeException( 'No conversion for criterion ' . get_class( $criterion ) . ' found.' );
+        throw new NotImplementedException( "No visitor available for: " . get_class( $criterion ) . ' with operator ' . $criterion->operator );
     }
 }
Throw not implemented exception for unknown criteria in legacy search