diff --git a/eZ/Bundle/EzPublishDebugBundle/Twig/DebugTemplate.php b/eZ/Bundle/EzPublishDebugBundle/Twig/DebugTemplate.php
index 0d10379826..89f65d27d7 100644
--- a/eZ/Bundle/EzPublishDebugBundle/Twig/DebugTemplate.php
+++ b/eZ/Bundle/EzPublishDebugBundle/Twig/DebugTemplate.php
@@ -76,9 +76,9 @@ public function getSourceContext(): Source
         return new Source('', '');
     }
 
-    protected function doDisplay(array $context, array $blocks = []): string
+    protected function doDisplay(array $context, array $blocks = []): iterable
     {
-        return '';
+        return [];
     }
 
     /**