How To Log Uncaught Exceptions In Python?

Better Stack Team

Updated on February 3, 2023

For this, you can use the sys.excepthook that allows us to attach a handler for any unhandled exception:

#Creating a logger
logger = logging.getLogger(__name__)
logging.basicConfig(filename='example.log', filemode='w', level=logging.DEBUG)

#Creating a handler
def handle_unhandled_exception(exc_type, exc_value, exc_traceback):
    if issubclass(exc_type, KeyboardInterrupt):
                #Will call default excepthook
        sys.__excepthook__(exc_type, exc_value, exc_traceback)
        return
        #Create a critical level log message with info from the except hook.
    logger.critical("Unhandled exception", exc_info=(exc_type, exc_value, exc_traceback))
#Assign the excepthook to the handler
sys.excepthook = handle_unhandled_exception

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First, you will create a logger that will take care of your exceptions.

Then create a handler handle_unhandled_exception that you will later attach to the hook. Then call the __excepthook__ provided by the sys module. This method is invoked every time the exception is uncaught.

Use the info from the hook to create a log message and assign this handler to the sys.excepthook.

You can learn more info about sys.excepthook in the offical documentation..

If you are new to logging in Python, please feel free read our Introduction to Python logging and learn more.