Lingua-e
Python

What is a NotADirectoryError?

← Errors

NotADirectoryError is raised when a directory operation is attempted on a path that is not a directory. It is a subclass of OSError. This commonly happens when a file path is passed where a directory path is expected.

Why it happens

  • •Calling os.listdir() or Path.iterdir() on a file path.
  • •Using os.chdir() with a path pointing to a file.
  • •A path component in a longer path resolves to a file instead of a directory.
  • •Passing the wrong variable to a function that expects a directory.

Examples

Python

Code that triggers the error

import os
os.listdir("myfile.txt")  # it's a file, not a directory

Error output

NotADirectoryError: [Errno 20] Not a directory: 'myfile.txt'

How to fix it

Always validate paths with Path.is_dir() before performing directory operations. Use pathlib for clearer path handling. When building paths dynamically, verify each component to detect unexpected file-vs-directory mismatches early.

Fixed code

from pathlib import Path

p = Path("myfile.txt")
if p.is_dir():
    for item in p.iterdir():
        print(item)
else:
    print(f"{p} is not a directory")

Related errors

Ready to practice your English at work?

Lingua-e has interactive exercises built around real developer conversations: standups, code reviews, retrospectives, and more. Practice until it comes naturally.

Try Lingua-e for free