Troubleshooting & Problem Resolution Flashcards

A `FileNotFoundError` is raised when opening a file. Which debugging step should you take first?

Answer: Print or log the exact file path being used at runtime

Runtime paths often differ from what developers assume; printing the resolved path immediately reveals mismatches.

You catch an exception with `except Exception as e:` but lose the original traceback. How do you re-raise it with the full traceback intact?

Answer: Use `raise` with no arguments inside the except block

A bare `raise` inside an except block re-raises the current exception preserving its original traceback.

Your unit test passes locally but fails in CI because a file path uses backslashes. What is the portable fix?

Answer: Use os.path.join() or pathlib.Path() to construct paths

`os.path.join()` and `pathlib.Path` use the correct separator for the current OS, making paths platform-independent.

A `UnicodeDecodeError` occurs when reading a file. Which argument to `open()` most likely fixes it?

Answer: encoding='utf-8'

Specifying the correct encoding (commonly UTF-8) tells Python how to decode the raw bytes in the file.

You have an infinite loop in a running Python script. Which is the quickest way to stop it without killing the terminal?

Answer: Press Ctrl+C to send a KeyboardInterrupt

Ctrl+C sends SIGINT to the process, which Python converts to a `KeyboardInterrupt` and stops the loop.

After refactoring, you get `AttributeError: module 'mymodule' has no attribute 'helper'`. What should you check first?

Answer: Whether the function was renamed or deleted in mymodule.py

The error directly states the attribute is missing, so verifying the module's current contents is the logical first step.

A script occasionally raises `ZeroDivisionError` depending on input data. What is the best defensive approach?

Answer: Validate the divisor before dividing and handle the zero case explicitly

Checking preconditions (guard clauses) prevents the error from occurring rather than catching it after the fact.