FileNotFoundError: No such file or directory

A FileNotFoundError occurs when Python tries to access or open a file that does not exist at the specified path. This typically happens due to:

1. Incorrect file path
2. File not existing in the given location
3. Wrong working directory
4. Misspelled file name
5. Lack of required permissions

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1. Common Causes and Fixes

Cause 1: Incorrect File Path

Python needs the correct path to locate the file. If the path is incorrect, it will raise a FileNotFoundError.

Incorrect Code:

with open("data.txt", "r") as file:
    content = file.read()

Solution: Ensure the file exists in the expected directory.
Check the path manually or use an absolute path instead of a relative one.

with open("/absolute/path/to/data.txt", "r") as file:
    content = file.read()

Check File Path Dynamically

import os
print(os.getcwd())  # Prints current working directory

Ensure that the file exists in the printed directory.

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Cause 2: File Does Not Exist

If the file doesn’t exist, Python will throw an error.

Fix: Check Before Accessing

import os

file_path = "data.txt"

if os.path.exists(file_path):
    with open(file_path, "r") as file:
        content = file.read()
else:
    print(f"Error: The file '{file_path}' does not exist.")

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Cause 3: Wrong Working Directory

Sometimes, the script runs from a different directory than expected.

Fix: Use os.path.abspath() to check the full path

import os

file_path = "data.txt"
print(os.path.abspath(file_path))  # Check the full path

Make sure the file exists at the printed path.

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Cause 4: Misspelled File Name

A minor typo can cause Python to not find the file.

Fix: Check Spelling and Extensions

# Ensure the file name is correct
file_path = "Data.txt"  # File is "Data.txt", but we're looking for "data.txt"
with open(file_path, "r") as file:
    content = file.read()

Windows is case-insensitive, but Linux and macOS are case-sensitive.

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Cause 5: Incorrect Permissions

If the file exists but Python lacks read permissions, it will trigger an error.

Fix: Change File Permissions

chmod +r data.txt  # Linux/macOS: Add read permission

Or run the script with administrative privileges.

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Cause 6: Trying to Read a Non-Existent File Instead of Creating It

If you’re trying to read ("r" mode) a file that doesn’t exist, Python will throw an error.

Fix: Use "w" or "a" mode to create the file if it doesn’t exist.

with open("data.txt", "w") as file:  # 'w' creates the file if not found
    file.write("Hello, world!")