>>> import argparse >>> parser = argparse.ArgumentParser(exit_on_error=False) >>> parser.parse_args(["--unknown"]) usage: [-h] : error: unrecognized arguments: --unknown The docs https://docs.python.org/3.10/library/argparse.html#exit-on-error say: > Normally, when you pass an invalid argument list to the parse_args() method of an ArgumentParser, it will exit with error info. > If the user would like catch errors manually, the feature can be enable by setting exit_on_error to False: This description _appears_ to be at odds with the observed behavior.