diff --git a/app.py b/app.py
index 1a3e0cc..a358efc 100644
--- a/app.py
+++ b/app.py
@@ -201,7 +201,10 @@ def add():
                 response_data = {"message": "Fail to add new item"}
                 return jsonify(response_data), 400
         except Exception as e:
-            error_message = str(e)
+            if hasattr(e, "message"):
+                error_message = e.message
+            else:
+                error_message = str(e)
             response_data = {"message": error_message}
             return jsonify(response_data), 400