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Logging options in Langflow

Langflow uses the loguru library for logging.

The default log_level is ERROR. Other options are DEBUG, INFO, WARNING, and CRITICAL.

The default logfile is called langflow.log, and its location depends on your operating system.

  • Linux/WSL: \~/.cache/langflow/
  • macOS: /Users/\<username\>/Library/Caches/langflow/
  • Windows: %LOCALAPPDATA%\langflow\langflow\Cache

The LANGFLOW_LOG_ENV controls log output and formatting. The container option outputs serialized JSON to stdout. The container_csv option outputs CSV-formatted plain text to stdout. The default (or not set) logging option outputs prettified output with RichHandler.

To modify Langflow's logging configuration, add them to your .env file and start Langflow.


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LANGFLOW_LOG_LEVEL=ERROR
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LANGFLOW_LOG_FILE=path/to/logfile.log
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LANGFLOW_LOG_ENV=container

To start Langflow with the values from your .env file, start Langflow with uv run langflow run --env-file .env

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