diff --git a/examples/custom_env/pettingzoo_env.py b/examples/custom_env/pettingzoo_env.py
index 8b173449..d5644b7b 100644
--- a/examples/custom_env/pettingzoo_env.py
+++ b/examples/custom_env/pettingzoo_env.py
@@ -25,6 +25,7 @@
 from openrl.selfplay.wrappers.random_opponent_wrapper import RandomOpponentWrapper
 
 register("RockPaperScissors", RockPaperScissors)
+
 env = make(
     "RockPaperScissors",
     env_num=10,
diff --git a/examples/custom_env/rock_paper_scissors.py b/examples/custom_env/rock_paper_scissors.py
index 7d5649d1..71d0fa74 100644
--- a/examples/custom_env/rock_paper_scissors.py
+++ b/examples/custom_env/rock_paper_scissors.py
@@ -54,7 +54,7 @@ class RockPaperScissors(AECEnv):
 
     metadata = {"render_modes": ["human"], "name": "rps_v2"}
 
-    def __init__(self, render_mode=None):
+    def __init__(self, id, render_mode=None):
         """
         The init method takes in environment arguments and
          should define the following attributes:
@@ -122,8 +122,8 @@ def observe(self, agent):
         """
         # observation of one agent is the previous state of the other
         # return np.array(self.observations[agent])
-        obs = np.zeros(4, dtype=np.int64)
-        obs[self.observations[agent]] = 1
+        obs = np.zeros([1, 4], dtype=np.int64)
+        obs[0, self.observations[agent]] = 1
         return obs
 
     def close(self):
diff --git a/openrl/selfplay/wrappers/base_multiplayer_wrapper.py b/openrl/selfplay/wrappers/base_multiplayer_wrapper.py
index a3de3c0f..5cd6116c 100644
--- a/openrl/selfplay/wrappers/base_multiplayer_wrapper.py
+++ b/openrl/selfplay/wrappers/base_multiplayer_wrapper.py
@@ -147,10 +147,18 @@ def _step(self, action):
                 if termination or truncation:
                     return (
                         copy.copy(self.env.observe(self.self_player)),
-                        self.env.rewards[self.self_player],
+                        (
+                            self.env.rewards[self.self_player]
+                            if self.self_player in self.env.rewards
+                            else 0
+                        ),
                         termination,
                         truncation,
-                        self.env.infos[self.self_player],
+                        (
+                            self.env.infos[self.self_player]
+                            if self.self_player in self.env.rewards
+                            else {}
+                        ),
                     )
 
                 else: