Python Error Handling: Best Practices for try, except, and Custom Exceptions
Bare except clauses hide bugs. Here is how I structure error handling to catch the right things and fail loudly on the rest. Error handling in Python is done with try and except , but using them well requires more discipline than the syntax suggests. I have seen codebases where every function was wrapped in a bare except Exception that silently swallowed errors, making bugs invisible. Good error handling means catching specific exceptions, failing loudly on the unexpected, and using custom exceptions to communicate failure modes clearly. Catch Specific Exceptions A bare except: catches everything, including KeyboardInterrupt and SystemExit , which means Ctrl-C stops working. Even except Exception: is too broad for most cases. I always specify the exception types I expect. # Bad: catches everything, hides bugs try: result = parse(data) except: result = None # Good: catches the expected failure try: result = parse(data) except (ValueError, KeyError) as e: logger.warning(f'Parse failed: {e}') result = None By naming the exceptions, I document what can go wrong. If a different exception occurs. say, a TypeError from a bug in parse . it propagates and surfaces during development instead of being silently converted to…