diff --git a/modules/backend/lang/en/lang.php b/modules/backend/lang/en/lang.php
index b2508e0fa0..06fa1540bb 100644
--- a/modules/backend/lang/en/lang.php
+++ b/modules/backend/lang/en/lang.php
@@ -319,7 +319,6 @@
         'select_page' => 'Select a page...',
     ],
     'relation' => [
-        'missing_behavior' => 'You must implement the RelationController behavior in your :controller controller.',
         'missing_behavior' => 'Field ":field" requires the ":controller" controller to implement the "RelationController" behavior.',
         'missing_config' => "Relation behavior does not have any configuration for ':config'.",
         'missing_definition' => "Relation behavior does not contain a definition for ':field'.",