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LangChain fails to return valid structured output

2 posts from 2 people2d activeSteady, +1 this weekunverified

Posts per day

Posts per day2 posts, Oct 27 to Nov 9

The posts behind it

GitHub issueslangchain-ai/langchain · QHarshilNov 4

fix(langchain): match `handle_errors` types against the wrapped parsing error

### Submission checklist - [x] This is a bug, not a usage question. - [x] I added a clear and descriptive title that summarizes this issue. - [x] I used the GitHub search to find a similar question and didn't find it. - [x] I am sure that this is a bug in LangChain rather than...

3 replies
GitHub issueslangchain-ai/langchain · Bear0117Oct 27

`InjectedToolCallId` is never injected when `args_schema` is a JSON schema dict (`TypeError: missing 1 required positional argument`)

...(and that raises the "tool must always be invoked with a full model ToolCall" error when no id is available). `_injected_args_keys` does detect the parameter for this tool (`frozenset({'tool_call_id'})`); it is just never acted on for dict schemas. Expected:...

2 replies

Companies and products named

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About this problem

Evidence

2 posts from 2 people in 1 place, about 1 a week over 9 days. Mostly on langchain-ai/langchain. Tools named alongside: GitHub, Anthropic, OpenAI, Perplexity.

Frustration Frustration 0 of 3· Seen on GitHub issues

How it was grouped

Posts that state a pain and match the "structured-output" rule about LangChain. First post Oct 27, 2026, latest Nov 4, 2026. Unverified: fewer than 3 posts, or one person or place only. Method

The same problem elsewhere

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Other LangChain problems

LangChain users keep filing bugs

Top post: "langchain 1.4.0: any after_model middleware using documented `jump_to=tools` bypasses the HITL", one of 27 posts from 23 people on GitHub issues, Reddit.

LangChain upgrades break working setups

10 posts from 10 people on GitHub issues, Reddit.

Trouble with LangChain agent

Top post: "langchain-classic: importing a moved agent from `agent_toolkits` raises `ValueError` instead of `ImportError`", one of 8 posts from 7 people on GitHub issues, Reddit, Stack Overflow.

RAG on LangChain returns irrelevant or missing context

8 posts from 7 people on Reddit, GitHub issues, Stack Overflow.

LangChain agents loop, stall or fail midway

5 posts from 5 people on Reddit, GitHub issues.

LangChain rate limits and usage caps block work

4 posts from 3 people on GitHub issues.

Trouble with LangChain test

Top post: "langchain: MCP adapter test asserts a POSIX-only error message, fails on Windows where the drive letter", one of 4 posts from 4 people on GitHub issues.

Trouble with LangChain agents

Top post: "Is it normal for a LangGraph supervisor to consume as many tokens as all 8 agents combined? How can we", one of 4 posts from 4 people on Reddit.

LangChain error messages are cryptic

3 posts from 2 people on GitHub issues.

LangChain vulnerabilities are hard to triage and patch

3 posts from 1 person on GitHub issues. Unverified.

Prompt injection makes LangChain features unsafe

3 posts from 2 people on Reddit, GitHub issues.

LangChain lock-in makes switching costly

2 posts from 2 people on GitHub issues. Unverified.

History

First seen with 2 posts.

Nov 6, 2026