Python

TypeError: expected str, bytes or os.PathLike object, not list — Python Error Causes and How to Fix It

You are building a FastAPI endpoint that accepts a list of file paths. You write `os.path.exists(files)` where `files` is a list — and Python crashes with `TypeError: expected str, bytes or os.PathLike object, not list`. It trips up nearly every developer working with file handling in FastAPI, Django, or any Python framework that accepts lists. Here is exactly why it happens and how to fix it instantly.