Python

FileNotFoundError: What It Means and How to Fix It

Error reference

FileNotFoundError

Language

Python

Severity

Medium

When it happens

A FileNotFoundError is raised in Python when the interpreter tries to open or access a file that does not exist at the given path.

Potential fixes

Use pathlib.Path and check .exists() before opening. Print or log the resolved absolute path with Path.resolve() to confirm you are looking in the right place. When bundling scripts, use __file__ to build paths relative to the script's own location rather than the current working directory.

Related errors

ImportError AttributeError

Deep dive

A FileNotFoundError is raised in Python when the interpreter tries to open or access a file that does not exist at the given path. It is a subclass of OSError and is the most common file-system error you will encounter.

Why it happens

•The file path is relative and the working directory is not what you expect when the script runs.
•A typo or incorrect path separator in the file path string.
•The file was deleted, moved, or never created before the script ran.
•The path points to a directory, not a file.

Potential fixes

Use pathlib.Path and check .exists() before opening. Print or log the resolved absolute path with Path.resolve() to confirm you are looking in the right place. When bundling scripts, use __file__ to build paths relative to the script's own location rather than the current working directory.

Examples

Python

Code that triggers the error

with open("config.json") as f:
    data = f.read()

Error output

Traceback (most recent call last):
  File "app.py", line 1, in <module>
    with open("config.json") as f:
FileNotFoundError: [Errno 2] No such file or directory: 'config.json'

Fixed code

from pathlib import Path

config_path = Path("config.json")

if config_path.exists():
    with config_path.open() as f:
        data = f.read()
else:
    print("Config file not found, using defaults")
    data = "{}"

Practice in English

How would you explain a FileNotFoundError to a fellow dev? Choose the right phrase:

"I hit an error...

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