diff --git a/backend/chainlit/data/chainlit_data_layer.py b/backend/chainlit/data/chainlit_data_layer.py
index d2fb2d9f62..438fa4c40d 100644
--- a/backend/chainlit/data/chainlit_data_layer.py
+++ b/backend/chainlit/data/chainlit_data_layer.py
@@ -378,10 +378,10 @@ async def create_step(self, step_dict: StepDict):
             "id": step_dict["id"],
             "thread_id": step_dict.get("threadId"),
             "parent_id": step_dict.get("parentId"),
-            "input": step_dict.get("input"),
+            "input": step_dict.get("input") or None,
             "metadata": json.dumps(step_dict.get("metadata", {})),
             "name": step_dict.get("name"),
-            "output": step_dict.get("output"),
+            "output": step_dict.get("output") or None,
             "type": step_dict["type"],
             "start_time": timestamp,
             "end_time": timestamp,