---
title: Troubleshooting and FAQ
sidebarTitle: Troubleshooting and FAQ
description: Troubleshooting and FAQ for Langfuse Evaluation.
---

# Troubleshooting and FAQ

This page addresses frequently asked questions and common troubleshooting topics for Langfuse Evaluation.

If you don't find a solution to your issue here, try using [Ask AI](/docs/ask-ai) for instant answers. For bug reports, please open a ticket on [GitHub Issues](/issues). For general questions or support, visit our [support page](/support).

## FAQ

- [How do I upgrade trace-level evaluators to observation-level evaluators?](/faq/all/llm-as-a-judge-migration)
- [How do I work with the observations table in Langfuse v4?](/faq/all/explore-observations-in-v4)
- [How to create and manage Score Configs in Langfuse?](/faq/all/manage-score-configs)
- [How to retrieve experiment scores via UI or API/SDK?](/faq/all/retrieve-experiment-scores)
- [How to use Langfuse-hosted Evaluators on Dataset Runs?](/faq/all/langfuse-evaluators-on-dataset-runs)
- [I have setup Langfuse, but I do not see any traces in the dashboard. How to solve this?](/faq/all/missing-traces)
- [What are scores in Langfuse and when should I use them?](/faq/all/what-are-scores)
- [Why do observation lookups with the v3 SDK return 404?](/faq/all/v3-sdk-observation-lookup-404)
- [Why is my observation-level evaluator not executing?](/faq/all/observation-eval-not-executing)

[Ask another question](/docs/ask-ai)

## GitHub Discussions

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## Agent Instructions

This page is part of the [Langfuse](https://langfuse.com) documentation, published as plain Markdown for AI agents. Every page is available as Markdown by appending `.md` to its URL, or by sending an `Accept: text/markdown` header. This page: `https://langfuse.com/docs/evaluation/more/troubleshooting-and-faq.md`.

### Querying these docs

If the answer is not on this page, query the documentation instead of guessing:

- **Semantic search** across all Langfuse docs, returning an answer with the relevant pages and excerpts. Ask a specific, self-contained question:

  ```bash
  curl -sG "https://langfuse.com/api/search-docs" --data-urlencode "query=How do I trace a LangGraph agent?"
  ```

- **Index of every page**: <https://langfuse.com/llms.txt>, with per-section indexes [llms-docs.txt](https://langfuse.com/llms-docs.txt), [llms-integrations.txt](https://langfuse.com/llms-integrations.txt), and [llms-self-hosting.txt](https://langfuse.com/llms-self-hosting.txt).

### Before writing Langfuse code

- **Install the [Langfuse Agent Skill](https://langfuse.com/docs/api-and-data-platform/features/agent-skill).** It encodes Langfuse's own best practices for instrumentation, prompt management, and evaluation, and materially improves results.
- **Read [What does a good trace look like?](https://langfuse.com/docs/observability/best-practices.md)** before instrumenting an application.
- **Verify endpoints, parameters, and response fields** against the [API reference](https://api.reference.langfuse.com) instead of inferring them from code examples.
- **Use the [Langfuse CLI](https://langfuse.com/docs/api-and-data-platform/features/cli)** (`npx @langfuse/cli api <resource> <action>`) to read or write traces, prompts, datasets, and scores from the terminal.

Found an error in these docs? Please open an issue at <https://github.com/langfuse/langfuse-docs/issues>.