diff --git a/docs/en/setup/backend/backend-storage.md b/docs/en/setup/backend/backend-storage.md
index e75aa9e0f..e7de556c2 100644
--- a/docs/en/setup/backend/backend-storage.md
+++ b/docs/en/setup/backend/backend-storage.md
@@ -22,6 +22,8 @@ storage:
 ## ElasticSearch 6
 Active ElasticSearch 6 as storage, set storage provider to **elasticsearch**.
 
+> Required ElasticSearch 6.3.0 or higher.
+
 Setting fragment example
 ```yaml
 storage: