agent_loop_mitigationTier 1 · 70% confidence
ai-agents-agent-loop-mitigatio-agent-loops-with-invalid-format-missing-action-err-1741b57a
agent: ai_agents
When does this happen?
IF Agent loops with 'Invalid Format: Missing Action:' error when using zero-shot-react-description with custom prompt that omits required 'Action:' tag after 'Thought:'.
How others solved it
THEN Ensure the format instructions include the exact required tags: 'Action:' after 'Thought:' and 'Action Input:' after 'Action:'. Alternatively, switch to the 'structured-chat-zero-shot-react-description' agent for more flexible format handling. Also set max_iterations (e.g., max_iterations=10) on the AgentExecutor to prevent infinite loops even if the model repeats.
agent = initialize_agent(tools, llm, agent='zero-shot-react-description', verbose=True, max_iterations=10, handle_parsing_errors=True, agent_kwargs={'format_instructions': """Use the following format: Thought: ...\nAction: ...\nAction Input: ...\nObservation: ..."""})Related patterns
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