Python FileNotFoundError: No such file or directory

3FileNotFoundError: explained step by step

A FileNotFoundError means Python tried to open, read or list a path and nothing exists there. The file may truly be missing, but more often the path is slightly wrong: a different folder, a typo, or a folder that was never created.

What the message is telling you

The full text is [Errno 2] No such file or directory: 'scores.txt'. The quoted part is the exact path you gave Python, character for character. Errno is the operating system's error number: you may see 2 on your computer and a different number in the browser editor, because the browser uses a small built-in file system. The class name is what matters.

try:
    with open("scores.txt") as f:
        data = f.read()
except FileNotFoundError as err:
    print("Class:", type(err).__name__)
    print("Path Python tried:", err.filename)

Reading is the default mode, so Python never creates a file for you when you open one with "r". The file handling lesson covers every mode.

How to read the traceback

Traceback (most recent call last):
  File "report.py", line 3, in <module>
    with open("data/scores.txt") as f:
FileNotFoundError: [Errno 2] No such file or directory: 'data/scores.txt'

1. The last line gives the exact path that failed. Compare it with where the file really lives.
2. The line above shows which open() call used that path.
3. If the path is built from variables, print it just before the call to see what Python sees.

Cause 1: the path is relative to a different folder

A relative path such as data/scores.txt is measured from the working directory, the folder the program was started from, and not from the folder where your script file sits. Starting the same script from another folder changes the result. On your own machine, print the working directory to find out:

python -c "import os; print(os.getcwd())"

Build paths with pathlib so they stay correct, and check them with exists():

from pathlib import Path

Path("project/data").mkdir(parents=True, exist_ok=True)
Path("project/data/prices.txt").write_text("4.50\n")

print(Path("project/data/prices.txt").exists())   # correct path
print(Path("project/prices.txt").exists())        # forgot the data folder

Cause 2: a typo, wrong case or hidden extension

Scores.txt, score.txt and scores.txt.txt are three different names. On Linux, macOS servers and in this browser editor, upper and lower case count as different letters. Some Windows setups also hide known extensions, so a file you think is notes.txt is really notes.txt.txt. List the folder with os.listdir() and compare the real names.

Cause 3: the file was never created

Opening a file for reading before anything has written it fails. If the program should create the file the first time it runs, open with "a" (append, creates when missing) or catch the error and create a default.

Cause 4: the folder does not exist when you write

Even open("reports/out.txt", "w") raises this error when reports is missing. Mode "w" creates the file, never the folder. Create the folder first:

import os

os.makedirs("reports_demo", exist_ok=True)
with open("reports_demo/out.txt", "w") as f:
    f.write("saved\n")
print(sorted(os.listdir("reports_demo")))

Cause 5: separators and escape sequences in Windows paths

In a normal string, "C:\new\table.txt" contains a newline (\n) and a tab (\t), so the path is nonsense. Use forward slashes (they work on every system), a raw string r"C:\new\table.txt", or Path("C:/new/table.txt").

Fix: check first, or catch the error

Use Path.exists() or is_file() when a missing file is an expected situation. Use try and except when the file might disappear between the check and the read, or you want one place that handles the problem. Always catch FileNotFoundError specifically. Combine either with the with statement so files close properly.

from pathlib import Path

settings = Path("settings_demo.txt")
settings.unlink(missing_ok=True)

try:
    theme = settings.read_text()
except FileNotFoundError:
    theme = "light"
    settings.write_text(theme)

print("Theme:", theme)
print("Saved:", settings.exists())

Similar errors that look related

FileNotFoundError is a subclass of OSError, as are PermissionError (you are not allowed to open the path) and IsADirectoryError (you tried to open a folder as if it were a file). FileExistsError appears when mode "x" is used on a file that already exists. Reading data formats such as CSV files or JSON uses the same open(), so the same causes and fixes apply.