diff --git a/lib/Controllers/DefaultController.php b/lib/Controllers/DefaultController.php
index f117d36..f02f262 100644
--- a/lib/Controllers/DefaultController.php
+++ b/lib/Controllers/DefaultController.php
@@ -42,7 +42,6 @@ class DefaultController extends ControllerAbstract {
     private const ERR_INVALID_OPERATION = 'Invalid operation: ';
     private const ERR_INVALID_PROVIDER = 'Invalid parameter: provider must be a string';
     private const ERR_INVALID_SERVICE = 'Invalid parameter: service must be a string';
-    private const ERR_INVALID_COLLECTION = 'Invalid parameter: collection must be a string';
     private const ERR_INVALID_IDENTIFIER = 'Invalid parameter: identifier must be a string';
     private const ERR_INVALID_SOURCES = 'Invalid parameter: sources must be an array';
     private const ERR_INVALID_TARGET = 'Invalid parameter: target must be an array';