TypeError: Object of type AgentChatResponse is not JSON serializable

Getting this error while using chat_history for agent chat in Llama Index. Need a quick resolution. Any help on this? You can get the code below-

'''chat_history.append(ChatMessage(role= MessageRole.USER, content=user_message))

response = agent.chat(message=user_message, chat_history= chat_history)

chat_history.append(ChatMessage(role= MessageRole.ASSISTANT, content=response))'''

It is working fine for the 1st time query and giving the error from 2nd one.

Any quick fix?