---
title: Can I cancel a running experiment?
seoTitle: "Stop or Cancel a Running Experiment"
description: Langfuse has no cancel action for running experiments. SDK experiments run in your process; experiments started from the UI run until all dataset items are processed.
tags: [evaluation, experiments]
---

# Can I cancel a running experiment?

There is no cancel or stop action for experiments in the Langfuse UI or API.

- **Experiments run with the SDK** (`run_experiment` / `experiment.run`) execute in your own process. Stop the process to stop the experiment. Items that already finished stay in Langfuse.
- **Experiments started from the UI** run in the Langfuse worker until every dataset item is processed. They cannot be stopped once started.

To limit the impact of a mistake, try a prompt or model on a small dataset first. To remove the results of an experiment afterwards, see [Delete experiment data](/faq/all/deprecated-api-migration#dataset-delete-sdk-methods).

See [Experiments via SDK](/docs/evaluation/experiments/experiments-via-sdk) and [Experiments via UI](/docs/evaluation/experiments/experiments-via-ui).

<!-- agent-instructions -->

---

## 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/faq/all/cancel-running-experiment.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>.