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Troubleshooting and FAQ

This page addresses frequently asked questions and common troubleshooting topics for the Langfuse Python SDK.

If you don’t find a solution to your issue here, try using Ask AI for instant answers. For bug reports, please open a ticket on GitHub Issues. For general questions or support, visit our support page.

  • Authentication Issues:
    • Ensure LANGFUSE_PUBLIC_KEY, LANGFUSE_SECRET_KEY, and LANGFUSE_HOST (if not using default cloud) are correctly set either as environment variables or in the Langfuse() constructor.
    • Use langfuse.auth_check() after initialization to verify credentials. Do not use this in production as this method waits for a response from the server.
  • No Traces Appearing:
    • Check if tracing_enabled is True (default).
    • Verify sample_rate is not 0.0.
    • Ensure langfuse.shutdown() is called or the program exits cleanly to allow atexit hooks to flush data. Manually call langfuse.flush() to force data sending.
    • Enable debug logging (debug=True or LANGFUSE_DEBUG="True") to see SDK activity and potential errors during exporting.
  • Incorrect Nesting or Missing Spans:
    • If you are self-hosting Langfuse, the Python SDK v3 requires Langfuse platform version >= 3.63.0 for traces to be correctly processed. You can find a snapshot of the legacy v2 SDK documentation here.
    • Ensure you are using context managers (with langfuse.start_as_current_span(...)) for proper context propagation.
    • If manually creating spans (langfuse.start_span()), ensure they are correctly ended with .end().
    • In async code, ensure context is not lost across await boundaries if not using Langfuse’s async-compatible methods.
  • Langchain/OpenAI Integration Not Working:
    • Confirm the respective integration (e.g., from langfuse.openai import openai or LangfuseCallbackHandler) is correctly set up before the calls to the LLM libraries are made.
    • Check for version compatibility issues between Langfuse, Langchain, and OpenAI SDKs.
  • Media Not Appearing:
    • Ensure LangfuseMedia objects are correctly initialized and passed in input, output, or metadata.
    • Check debug logs for any media upload errors. Media uploads happen in background threads.

If you encounter persistent issues, please:

  1. Enable debug logging to gather more information.
  2. Check the Langfuse status page (if applicable for cloud users).
  3. Raise an issue on our GitHub repository with details about your setup, SDK version, code snippets, and debug logs.
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