Logging

This article explains how to control level of the logs messages generated by Flet library and its underlying components. You may need to enable detailed logging to troubleshoot Flet library or when submitting a new Flet issue.

Python

Flet Python modules expose named loggers: flet_core and flet.

To enable detailed/verbose Flet logging in your program add this code before calling ft.app():

import logging
logging.basicConfig(level=logging.DEBUG)

This will enable loggers across all Flet modules (flet_core and flet).

To reduce verbosity you may suppress logging messages from flet_core module, but adding:

logging.getLogger("flet_core").setLevel(logging.INFO)

Debug logging is usually needed for troubleshooting purposes, when submitting a new Flet issue.

In the most cases you should be fine with INFO logging level.

Fletd server

You can control the logging of Fletd - built-in Flet web server.

When flet Python logger level is configured its value is implicitly passed to Fletd server and you can see its log messages in the output.

However, you can use FLET_LOG_LEVEL environment variable to override Fletd log level: debug, info, warning, debug, panic, fatal.

Additionally, to redirect Flet logs output to a file you can set FLET_LOG_TO_FILE environment variable to true. Flet logs will be saved to /tmp/flet-server.log on macOS and Linux and to %TEMP%\flet-server.log on Windows.