---
title: How long does it take for traces to appear in Langfuse?
description: "Traces usually appear in Langfuse within seconds of the SDK flushing. Why there is a short delay, and what to check when it takes longer."
tags: [observability, tracing]
---

# How long does it take for traces to appear in Langfuse?

Traces typically appear in Langfuse within seconds of being flushed by the SDK. The Langfuse SDKs send trace data asynchronously in batches, so there is a short gap between an operation running in your application and the corresponding trace being visible in the UI. See [queuing and batching](/docs/observability/features/queuing-batching) for how this works and how to tune it.

Two factors determine the delay you see:

1. **Flushing**: The SDK must flush its event queue before data is sent. Long-running applications flush automatically on an interval. In short-lived environments such as serverless functions, batch scripts, or notebooks, flush manually before the process exits, otherwise events can be lost or delayed.
2. **Ingestion path**: On Langfuse Cloud with the Langfuse v4 preview enabled, data sent via Python SDK v4.7.0+, JS/TS SDK v5.4.0+, or direct OpenTelemetry ingestion with the `x-langfuse-ingestion-version: 4` header appears in the unified tracing table in real time. Data sent via older SDK versions, or via direct OpenTelemetry ingestion without that header, can appear with a delay of up to 15 minutes. See [Working with the observations table](/faq/all/explore-observations-in-v4) for upgrade steps.

If traces still do not appear after a few minutes, work through the [missing traces troubleshooting guide](/faq/all/missing-traces). On self-hosted instances, see [missing events after ingestion](/faq/all/self-hosting-missing-events-after-ingestion).

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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/faq/all/how-long-until-traces-appear.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>.