diff --git a/conf/defaults.ini b/conf/defaults.ini
index cb841e57cf9..dfa6bf99017 100644
--- a/conf/defaults.ini
+++ b/conf/defaults.ini
@@ -476,6 +476,7 @@ sampler_param = 1
 provider =
 
 [external_image_storage.s3]
+bucket_url =
 bucket =
 region =
 access_key =