diff --git a/api/apps/sdk/session.py b/api/apps/sdk/session.py
index 05e5bb838..e9edab8b2 100644
--- a/api/apps/sdk/session.py
+++ b/api/apps/sdk/session.py
@@ -464,12 +464,11 @@ def list_session(tenant_id, chat_id):
         if conv["reference"]:
             messages = conv["messages"]
             message_num = 0
-            chunk_num = 0
             while message_num < len(messages):
                 if message_num != 0 and messages[message_num]["role"] != "user":
                     chunk_list = []
-                    if "chunks" in conv["reference"][chunk_num]:
-                        chunks = conv["reference"][chunk_num]["chunks"]
+                    if "chunks" in conv["reference"][message_num]:
+                        chunks = conv["reference"][message_num]["chunks"]
                         for chunk in chunks:
                             new_chunk = {
                                 "id": chunk.get("chunk_id", chunk.get("id")),
@@ -482,7 +481,6 @@ def list_session(tenant_id, chat_id):
                             }
 
                             chunk_list.append(new_chunk)
-                    chunk_num += 1
                     messages[message_num]["reference"] = chunk_list
                 message_num += 1
         del conv["reference"]