diff --git a/gymnasium/vector/vector_env.py b/gymnasium/vector/vector_env.py
index 29b5e1c22..84e7b9a1b 100644
--- a/gymnasium/vector/vector_env.py
+++ b/gymnasium/vector/vector_env.py
@@ -190,6 +190,7 @@ def step(
             >>> infos
             {}
         """
+        raise NotImplementedError(f"{self.__str__()} step function is not implemented.")
 
     def render(self) -> tuple[RenderFrame, ...] | None:
         """Returns the rendered frames from the parallel environments.