Fix n8n MCP AI Agent OAuth2 Silent Tool Failure
The AI Agent says it used no tools and the run shows success - the real cause is an OAuth2 token n8n never refreshes in an MCP context.
Topic
Troubleshooting
Error-fixing (combine with How To)
Fix the Zapier Tables Cannot Create ULID 400 Error
The 400 'Cannot create ULID from string' error is a field-mapping mistake, not a broken table - here is how to feed Zapier Tables a valid Record ID.
Fix n8n's MCP Webhook Heap Leak in Queue Mode
Why memory climbs to an OOM crash on n8n workers running an MCP Trigger in queue mode, and the exact version that fixes the SessionManager leak.
How to fix Make's Retry error handler (formerly Break) not triggering
Make's Retry error handler (formerly Break) silently skips HTTP module failures until you flip one toggle on the HTTP module itself.
How to Fix LangChain AgentExecutor Not Calling Tools
AgentExecutor's verbose trace shows it choosing a tool, then the chain just finishes - no error, no tool result. Here's why, and the five-check fix.
Fix LangChain create_react_agent 'unexpected keyword argument prompt'
The TypeError comes from a kwarg rename between langgraph versions - or the wrong create_react_agent import entirely. Here's how to tell which and fix it.
How to fix Cursor's Terminal sandbox error on Linux (AppArmor)
Cursor's terminal sandbox fails on Ubuntu 24.04+, Fedora, and Arch because of an AppArmor namespace restriction -- here's the two-command fix and why chmod 4755 makes it worse.
Fix Claude Code MCP "Failed to Connect" (Bun Runtime Bug)
curl reaches your HTTP MCP server fine, but Claude Code's CLI still says 'Failed to connect' -- here's why the Bun runtime is the actual point of failure, and three ways around it.
Fix LangChain Output Parsing Errors (handle_parsing_errors=True)
handle_parsing_errors=True only retries LangChain's free-text ReAct loop -- it can't fix a model that won't format output reliably. Here's what actually works.
Cursor Override OpenAI Base URL Breaks Anthropic Key: Fix
One Cursor settings toggle causes three different Anthropic API key errors. Here is the exact fix and why it can silently undo itself.