diff --git a/Filer-Server-API.md b/Filer-Server-API.md
index a92cc24..fd0b42f 100644
--- a/Filer-Server-API.md
+++ b/Filer-Server-API.md
@@ -127,6 +127,8 @@ curl -X DELETE http://localhost:8888/path/to/a/file?tagging
 | PUT | <file_url>?tagging | Prefixed with "Seaweed-" | set the meta data  |
 | DELETE | <file_url>?tagging |  | remove all the "Seaweed-" prefixed header  |
 
+# notice
+`AutoChunking not supported for method PUT` so If the file length is greater than 256MB, only the previous 256MB will be saved.
 
 ### Create an empty folder