diff --git a/opendevin/server/session/msg_stack.py b/opendevin/server/session/msg_stack.py
index 36fc7da2a9..6e0862af44 100644
--- a/opendevin/server/session/msg_stack.py
+++ b/opendevin/server/session/msg_stack.py
@@ -99,7 +99,11 @@ class MessageStack:
                 new_data = {}
                 for sid, msgs in data.items():
                     if sid != del_sid:
-                        new_data[sid] = [msg.to_dict() for msg in msgs]
+                        new_data[sid] = msgs
+                # Move the file pointer to the beginning of the file to overwrite the original contents
+                file.seek(0)
+                # clean previous content
+                file.truncate()
                 json.dump(new_data, file)
         except FileNotFoundError:
             pass