Agent skill · research science · jeremylongshore
langchain-common-errors
Paste-match catalog of 14 real LangChain 1.0 / LangGraph 1.0 exceptions\
Why this skill is useful
Provides a catalog of specific LangChain and LangGraph exceptions with named causes and fixes that the AI wouldn't reliably generate on its own.
What it needs
About 7k tokens when loaded. Last updated 2026-08-07. 2,604 stars on the source repository.
What this skill does
LangChain Common Errors (Python) Overview The same twelve-plus LangChain 1.0 / LangGraph 1.0 tracebacks show up every week in production: ImportError: cannot import name 'ChatOpenAI' from 'langchain.chatmodels', AttributeError: 'list' object has no attribute 'lower', GraphRecursionError: Recursion limit of 25 reached, TypeError: Object of type datetime is not JSON serializable, KeyError: 'question' deep in LCEL internals. Stack traces are ambiguous, docs sprawl across 0.2 / 0.3 / 1.0 eras, and engineers lose 30–90 minutes per incident re-deriving the fix. This skill is a paste-match catalog of 14 entries (E01–E14) grouped into 3 reference files by category, plus a triage decision tree. Every entry opens with the exact exception class and message string you see in your terminal, names the cause in one sentence with a pain-catalog code, and gives a one-line fix or a reference-file pointer. Pinned to langchain-core 1.0.x, langchain 1.0.x, langgraph 1.0.x, verified 2026-04-21. Pain-catalog anchors: P02, P06, P09, P10, P16, P17, P38, P39, P40, P41, P42, P55, P56, P57, P66. Prerequisites Python 3.10+ A traceback or a reproducible bug — this skill is diagnostic, not preventive langchain-core >= 1.0, < 2.0, langgraph >= 1.0, < 2.0, and any provider integration packages pinned to 1.0.x anthropic >= 0.42 when using langchain-anthropic 1.0 (see E06) Instructions 1. Triage first. Read the first line of the traceback. Look up the exception class in the catalog below or in Triage Decision Tree. 2. Match the message string, not the call site. Each catalog entry opens with the literal message pattern you see. 3. Apply the named fix. If the entry points to a reference file, read that file for the deep walk-through including codemods, before/after code, and adjacent traps. Otherwise use the one-line fix here. 4. Verify with a test. Every catalog entry names a test that will catch the error in CI next time. 5. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills jeremylongshore/langchain-common-errors--e1ecc9