File Handling Errors in Python

File handling errors occur when working with files, such as reading, writing, or opening a file that doesn’t exist. Python provides built-in error handling mechanisms to prevent crashes and handle exceptions gracefully.

Common Causes of File Handling Errors:

1. File Not Found – Trying to open a non-existent file.
2. Permission Denied – Lack of proper access rights.
3. File Already Exists – Issues when creating a file that already exists.
4. File is Opened Elsewhere – Another program locks the file.
5. Invalid File Path – Incorrect directory or file name.

Python handles these errors using exception handling (try-except).

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1. Handling “File Not Found” Error (FileNotFoundError)

Occurs when attempting to open a file that doesn’t exist.

try:
    with open("non_existent_file.txt", "r") as file:
        content = file.read()
except FileNotFoundError:
    print("Error: The file does not exist!")

Solution: Check if the file exists before opening it.

import os

if os.path.exists("non_existent_file.txt"):
    with open("non_existent_file.txt", "r") as file:
        content = file.read()
else:
    print("Error: The file does not exist!")

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2. Handling “Permission Denied” Error (PermissionError)

Occurs when trying to access a file without sufficient permissions.

try:
    with open("/root/protected_file.txt", "w") as file:
        file.write("Hello")
except PermissionError:
    print("Error: You do not have permission to access this file!")

Solution:

• Check file permissions (chmod on Linux/Mac, security settings on Windows).
• Run the script with administrator privileges.

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3. Handling “File Already Exists” Error (FileExistsError)

Occurs when creating a file that already exists.

try:
    with open("existing_file.txt", "x") as file:
        file.write("New file created")
except FileExistsError:
    print("Error: File already exists!")

Solution: Use "a" (append) mode instead of "x" if you want to update the file.

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4. Handling “Is a Directory” Error (IsADirectoryError)

Occurs when trying to open a directory as a file.

try:
    with open("my_folder", "r") as file:  # "my_folder" is a directory
        content = file.read()
except IsADirectoryError:
    print("Error: The specified path is a directory, not a file!")

Solution: Ensure that the path is a file before opening it.

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5. Handling “File is in Use” Error (OSError)

Occurs when another program has locked the file.

try:
    with open("locked_file.txt", "r") as file:
        content = file.read()
except OSError:
    print("Error: The file is currently in use by another program!")

Solution: Close the file in the other program before accessing it.

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6. Handling “Invalid File Path” Error (OSError)

Occurs when trying to open a file with an incorrect path.

try:
    with open("C:/InvalidPath/file.txt", "r") as file:
        content = file.read()
except OSError:
    print("Error: Invalid file path!")

Solution:

• Check if the path is correct.
• Use double backslashes (\\) in Windows paths or raw strings (r"path").

Example:

with open(r"C:\Users\Username\file.txt", "r") as file:
    content = file.read()

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7. Handling “Unsupported File Encoding” Error (UnicodeDecodeError)

Occurs when reading a file with the wrong encoding.

try:
    with open("file.txt", "r", encoding="utf-8") as file:
        content = file.read()
except UnicodeDecodeError:
    print("Error: File encoding issue!")

Solution: Specify the correct encoding (utf-8, latin-1, etc.).

with open("file.txt", "r", encoding="latin-1") as file:
    content = file.read()

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8. Using try-except-finally to Ensure File Closure

The finally block ensures the file is closed properly, even if an error occurs.

try:
    file = open("data.txt", "r")
    content = file.read()
except FileNotFoundError:
    print("Error: File not found!")
finally:
    file.close()  # Ensures file is closed

Better Alternative: Use with open() (auto-closes file).

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

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9. Checking If a File Exists Before Reading or Writing

import os

if os.path.exists("data.txt"):
    with open("data.txt", "r") as file:
        content = file.read()
else:
    print("Error: File does not exist!")

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10. Summary Table

Error Type	Exception	Cause	Solution
File Not Found	FileNotFoundError	File does not exist	Check existence with os.path.exists()
Permission Denied	PermissionError	No access rights	Change file permissions
File Already Exists	FileExistsError	Creating a file that exists	Use "a" mode instead of "x"
Trying to Open a Directory	IsADirectoryError	Opening a directory as a file	Ensure the path is a file
File in Use	OSError	File is locked by another program	Close the file in the other program
Invalid Path	OSError	Incorrect file path	Use correct file paths
Encoding Issue	UnicodeDecodeError	Wrong encoding used	Specify correct encoding (utf-8, latin-1)