diff --git a/autogen/agentchat/conversable_agent.py b/autogen/agentchat/conversable_agent.py
index 7b7ecaa80204..a3726678a452 100644
--- a/autogen/agentchat/conversable_agent.py
+++ b/autogen/agentchat/conversable_agent.py
@@ -1395,13 +1395,14 @@ def check_termination_and_human_reply(
         if config is None:
             config = self
         if messages is None:
-            messages = self._oai_messages[sender]
+            messages = self._oai_messages[sender] if sender else []
         message = messages[-1]
         reply = ""
         no_human_input_msg = ""
+        sender_name = "the sender" if sender is None else sender.name
         if self.human_input_mode == "ALWAYS":
             reply = self.get_human_input(
-                f"Provide feedback to {sender.name}. Press enter to skip and use auto-reply, or type 'exit' to end the conversation: "
+                f"Provide feedback to {sender_name}. Press enter to skip and use auto-reply, or type 'exit' to end the conversation: "
             )
             no_human_input_msg = "NO HUMAN INPUT RECEIVED." if not reply else ""
             # if the human input is empty, and the message is a termination message, then we will terminate the conversation
@@ -1414,9 +1415,9 @@ def check_termination_and_human_reply(
                     # self.human_input_mode == "TERMINATE":
                     terminate = self._is_termination_msg(message)
                     reply = self.get_human_input(
-                        f"Please give feedback to {sender.name}. Press enter or type 'exit' to stop the conversation: "
+                        f"Please give feedback to {sender_name}. Press enter or type 'exit' to stop the conversation: "
                         if terminate
-                        else f"Please give feedback to {sender.name}. Press enter to skip and use auto-reply, or type 'exit' to stop the conversation: "
+                        else f"Please give feedback to {sender_name}. Press enter to skip and use auto-reply, or type 'exit' to stop the conversation: "
                     )
                     no_human_input_msg = "NO HUMAN INPUT RECEIVED." if not reply else ""
                     # if the human input is empty, and the message is a termination message, then we will terminate the conversation
@@ -1427,7 +1428,7 @@ def check_termination_and_human_reply(
                 else:
                     # self.human_input_mode == "TERMINATE":
                     reply = self.get_human_input(
-                        f"Please give feedback to {sender.name}. Press enter or type 'exit' to stop the conversation: "
+                        f"Please give feedback to {sender_name}. Press enter or type 'exit' to stop the conversation: "
                     )
                     no_human_input_msg = "NO HUMAN INPUT RECEIVED." if not reply else ""
                     # if the human input is empty, and the message is a termination message, then we will terminate the conversation
@@ -1505,13 +1506,14 @@ async def a_check_termination_and_human_reply(
         if config is None:
             config = self
         if messages is None:
-            messages = self._oai_messages[sender]
-        message = messages[-1]
+            messages = self._oai_messages[sender] if sender else []
+        message = messages[-1] if messages else {}
         reply = ""
         no_human_input_msg = ""
+        sender_name = "the sender" if sender is None else sender.name
         if self.human_input_mode == "ALWAYS":
             reply = await self.a_get_human_input(
-                f"Provide feedback to {sender.name}. Press enter to skip and use auto-reply, or type 'exit' to end the conversation: "
+                f"Provide feedback to {sender_name}. Press enter to skip and use auto-reply, or type 'exit' to end the conversation: "
             )
             no_human_input_msg = "NO HUMAN INPUT RECEIVED." if not reply else ""
             # if the human input is empty, and the message is a termination message, then we will terminate the conversation
@@ -1524,9 +1526,9 @@ async def a_check_termination_and_human_reply(
                     # self.human_input_mode == "TERMINATE":
                     terminate = self._is_termination_msg(message)
                     reply = await self.a_get_human_input(
-                        f"Please give feedback to {sender.name}. Press enter or type 'exit' to stop the conversation: "
+                        f"Please give feedback to {sender_name}. Press enter or type 'exit' to stop the conversation: "
                         if terminate
-                        else f"Please give feedback to {sender.name}. Press enter to skip and use auto-reply, or type 'exit' to stop the conversation: "
+                        else f"Please give feedback to {sender_name}. Press enter to skip and use auto-reply, or type 'exit' to stop the conversation: "
                     )
                     no_human_input_msg = "NO HUMAN INPUT RECEIVED." if not reply else ""
                     # if the human input is empty, and the message is a termination message, then we will terminate the conversation
@@ -1537,7 +1539,7 @@ async def a_check_termination_and_human_reply(
                 else:
                     # self.human_input_mode == "TERMINATE":
                     reply = await self.a_get_human_input(
-                        f"Please give feedback to {sender.name}. Press enter or type 'exit' to stop the conversation: "
+                        f"Please give feedback to {sender_name}. Press enter or type 'exit' to stop the conversation: "
                     )
                     no_human_input_msg = "NO HUMAN INPUT RECEIVED." if not reply else ""
                     # if the human input is empty, and the message is a termination message, then we will terminate the conversation
diff --git a/test/agentchat/test_conversable_agent.py b/test/agentchat/test_conversable_agent.py
index 5b0a6c326b43..b71a6341c877 100644
--- a/test/agentchat/test_conversable_agent.py
+++ b/test/agentchat/test_conversable_agent.py
@@ -472,6 +472,29 @@ async def test_a_generate_reply_raises_on_messages_and_sender_none(conversable_a
         await conversable_agent.a_generate_reply(messages=None, sender=None)
 
 
+def test_generate_reply_with_messages_and_sender_none(conversable_agent):
+    messages = [{"role": "user", "content": "hello"}]
+    try:
+        response = conversable_agent.generate_reply(messages=messages, sender=None)
+        assert response is not None, "Response should not be None"
+    except AssertionError as e:
+        pytest.fail(f"Unexpected AssertionError: {e}")
+    except Exception as e:
+        pytest.fail(f"Unexpected exception: {e}")
+
+
+@pytest.mark.asyncio
+async def test_a_generate_reply_with_messages_and_sender_none(conversable_agent):
+    messages = [{"role": "user", "content": "hello"}]
+    try:
+        response = await conversable_agent.a_generate_reply(messages=messages, sender=None)
+        assert response is not None, "Response should not be None"
+    except AssertionError as e:
+        pytest.fail(f"Unexpected AssertionError: {e}")
+    except Exception as e:
+        pytest.fail(f"Unexpected exception: {e}")
+
+
 def test_update_function_signature_and_register_functions() -> None:
     with pytest.MonkeyPatch.context() as mp:
         mp.setenv("OPENAI_API_KEY", MOCK_OPEN_AI_API_KEY)