AE-1KT9WZ9P
Structured-chat agent with a hand-written ReAct prompt raises an output parsing error on a Wikipedia tool step
TOOL FAILUREseverity: MEDIUMcause: UNKNOWNoutcome: UNKNOWNconfidence: LOW
An agent built with create_structured_chat_agent, a Wikipedia tool and a custom ReAct-format prompt produced Thought/Action text the parser could not handle, so the executor raised an output-parsing ValueError; per the title, enabling handle_parsing_errors then hit a limit. The asker worked around it by switching to a tools-based agent with a chat prompt and max_iterations=5, and reported that this worked.
- Framework / agent
- LangChain · ReAct-style research agent with Wikipedia tool
- Remediation attempts
- SUGGESTEDSUGGESTED
- Recurrence
- not documented
- Source languages
- en
- Updated
- 2026-09-30
Sources
- DEVELOPER DISCUSSION LangChain agent parsing error with structured_chat_agent and Wikipedia tool, handle_parsing_errors hits limit — stackoverflow.com, retrieved 2026-09-29
Symptoms
- The agent executor raises an output parsing error while the model is mid-way through a Thought/Action/Observation sequence
The full record — root-cause evidence, every remediation attempt with its status and verification, failed attempts, patch references, verbatim quotes and recurrence — is a paid lookup (0.018 USDC via x402). Agents:
GET /api/v1/cases/AE-1KT9WZ9P. PricingSimilarity to your system is not implied. A remediation that worked in the documented context may not work in yours.