diff --git a/src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ConfigBuilderCacheWarmer.php b/src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ConfigBuilderCacheWarmer.php
index 81a0a26c7b384..9921dd2f57fec 100644
--- a/src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ConfigBuilderCacheWarmer.php
+++ b/src/Symfony/Bundle/FrameworkBundle/CacheWarmer/ConfigBuilderCacheWarmer.php
@@ -85,6 +85,6 @@ private function dumpExtension(ExtensionInterface $extension, ConfigBuilderGener
 
     public function isOptional(): bool
     {
-        return true;
+        return false;
     }
 }