diff --git a/OAI_CONFIG_LIST_sample b/OAI_CONFIG_LIST_sample
index 5f79236a60c..9789627af69 100644
--- a/OAI_CONFIG_LIST_sample
+++ b/OAI_CONFIG_LIST_sample
@@ -1,5 +1,7 @@
-// Please modify the content, remove these two lines of comment and rename this file to OAI_CONFIG_LIST to run the sample code.
-// if using pyautogen v0.1.x with Azure OpenAI, please replace "base_url" with "api_base" (line 11 and line 18 below). Use "pip list" to check version of pyautogen installed.
+// Please modify the content, remove these four lines of comment and rename this file to OAI_CONFIG_LIST to run the sample code.
+// If using pyautogen v0.1.x with Azure OpenAI, please replace "base_url" with "api_base" (line 13 and line 20 below). Use "pip list" to check version of pyautogen installed.
+//
+// NOTE: This configuration lists GPT-4 as the default model, as this represents our current recommendation, and is known to work well with AutoGen. If you use a model other than GPT-4, you may need to revise various system prompts (especially if using weaker models like GPT-3.5-turbo). Moreover, if you use models other than those hosted by OpenAI or Azure, you may incur additional risks related to alignment and safety. Proceed with caution if updating this default.
 [
     {
         "model": "gpt-4",
diff --git a/README.md b/README.md
index 3fe3139f873..dd9f4243988 100644
--- a/README.md
+++ b/README.md
@@ -58,6 +58,8 @@ The easiest way to start playing is
  2. Copy OAI_CONFIG_LIST_sample to ./notebook folder, name to OAI_CONFIG_LIST, and set the correct configuration.
  3. Start playing with the notebooks!
 
+*NOTE*: OAI_CONFIG_LIST_sample lists GPT-4 as the default model, as this represents our current recommendation, and is known to work well with AutoGen. If you use a model other than GPT-4, you may need to revise various system prompts (especially if using weaker models like GPT-3.5-turbo). Moreover, if you use models other than those hosted by OpenAI or Azure, you may incur additional risks related to alignment and safety. Proceed with caution if updating this default.
+
 ## Using existing docker image
 Install docker, save your oai key into an environment variable name OPENAI_API_KEY, and then run the following.
 
diff --git a/autogen/agentchat/conversable_agent.py b/autogen/agentchat/conversable_agent.py
index 08f71160057..e8b68fbc8ce 100644
--- a/autogen/agentchat/conversable_agent.py
+++ b/autogen/agentchat/conversable_agent.py
@@ -43,9 +43,7 @@ class ConversableAgent(Agent):
     To customize the initial message when a conversation starts, override `generate_init_message` method.
     """
 
-    DEFAULT_CONFIG = {
-        "model": DEFAULT_MODEL,
-    }
+    DEFAULT_CONFIG = {}  # An empty configuration
     MAX_CONSECUTIVE_AUTO_REPLY = 100  # maximum number of consecutive auto replies (subject to future change)
 
     llm_config: Union[Dict, Literal[False]]
@@ -1301,7 +1299,7 @@ def update_function_signature(self, func_sig: Union[str, Dict], is_remove: None)
             is_remove: whether removing the function from llm_config with name 'func_sig'
         """
 
-        if not self.llm_config:
+        if not isinstance(self.llm_config, dict):
             error_msg = "To update a function signature, agent must have an llm_config"
             logger.error(error_msg)
             raise AssertionError(error_msg)
diff --git a/test/agentchat/test_conversable_agent.py b/test/agentchat/test_conversable_agent.py
index 87868b05dff..5e8ac73ebfb 100644
--- a/test/agentchat/test_conversable_agent.py
+++ b/test/agentchat/test_conversable_agent.py
@@ -7,6 +7,14 @@
 from typing_extensions import Annotated
 
 from autogen.agentchat import ConversableAgent, UserProxyAgent
+from conftest import skip_openai
+
+try:
+    import openai
+except ImportError:
+    skip = True
+else:
+    skip = False or skip_openai
 
 
 @pytest.fixture
@@ -610,9 +618,24 @@ async def exec_sh(script: Annotated[str, "Valid shell script to execute."]):
         assert get_origin(user_proxy_1.function_map) == expected_function_map
 
 
+@pytest.mark.skipif(
+    skip,
+    reason="do not run if skipping openai",
+)
+def test_no_llm_config():
+    # We expect a TypeError when the model isn't specified
+    with pytest.raises(TypeError, match=r".*Missing required arguments.*"):
+        agent1 = ConversableAgent(name="agent1", llm_config=False, human_input_mode="NEVER", default_auto_reply="")
+        agent2 = ConversableAgent(
+            name="agent2", llm_config={"api_key": "Intentionally left blank."}, human_input_mode="NEVER"
+        )
+        agent1.initiate_chat(agent2, message="hi")
+
+
 if __name__ == "__main__":
     # test_trigger()
     # test_context()
     # test_max_consecutive_auto_reply()
     # test_generate_code_execution_reply()
-    test_conversable_agent()
+    # test_conversable_agent()
+    test_no_llm_config()