All 15 Logging questions
More in Logging
How do you include structured context (like a request ID) in every log message using LoggerAdapter or extra? What's the difference between propagate=True and propagate=False on a logger? What's the danger of using %-style, f-string, or .format() interpolation directly in a log call's message argument versus lazy % substitution? How do RotatingFileHandler and TimedRotatingFileHandler prevent log files from growing unbounded? Why is logging generally considered thread-safe, and what should you still be careful about in multiprocessing? How would you write a custom logging.Filter to redact sensitive data like passwords from log messages? How does logging.NullHandler help library authors avoid the 'No handlers could be found' warning?
Advertisement
Back to results for “Debugging”
Python › Logging

How does logger.exception() differ from logger.error(), and when should you use it?

Advanced

Answer

logger.exception(msg) is equivalent to logger.error(msg, exc_info=True) -- it automatically attaches the current exception's traceback to the log record. It should only be called from within an except block; calling it outside one logs 'NoneType: None' for the traceback since there's no active exception.
try:
    1 / 0
except ZeroDivisionError:
    logging.exception('Division failed')
    # Logs the error message AND the full traceback automatically
Real-world example A background job's except block calls logger.exception() so the full stack trace lands in the log file for later debugging, without manually calling traceback.format_exc().

Common follow-ups: What does exc_info=True actually capture?;How do you log a traceback without re-raising the exception?

Exception Handling;Debugging & Profiling
All 15 Logging questions