diff --git a/source/framework/11.x/validation.php b/source/framework/11.x/validation.php
index e207713b790..a0b0b8c1e0b 100644
--- a/source/framework/11.x/validation.php
+++ b/source/framework/11.x/validation.php
@@ -25,6 +25,7 @@
     'boolean'          => 'The :attribute field must be true or false.',
     'can'              => 'The :attribute field contains an unauthorized value.',
     'confirmed'        => 'The :attribute field confirmation does not match.',
+    'contains'         => 'The :attribute field is missing a required value.',
     'current_password' => 'The password is incorrect.',
     'custom'           => [
         'attribute-name' => [