Solve - ValueError: I/O operation on closed file in Python

Solve - ValueError: I/O operation on closed file in Python #

The Python "ValueError: I/O operation on closed file" occurs when we try to perform an operation on a closed file. To solve the error, make sure to indent the code that tries to access the file correctly if using the with open() statement.

valueerror io operation on closed file

Here is an example of how the error occurs.

main.py

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import csv

with open('employees.csv', 'w', newline='', encoding='utf-8') as csvfile:
    fieldnames = ['first_name', 'last_name']

    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
    print(csvfile.closed)  # 👉️ False


# 👇️ forgot to indent code 👇️

# ⛔️ ValueError: I/O operation on closed file.
print(csvfile.closed)  # 👉️ True
writer.writeheader()
writer.writerow({'first_name': 'Alice', 'last_name': 'Smith'})

We forgot to indent the code that writes to the file, so the with open() statement automatically closed the file and we performed an I/O operation on a closed file.

To solve th error, make sure to indent your code correctly and move it into the with statement without mixing tabs and spaces.

main.py

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import csv

with open('employees.csv', 'w', newline='', encoding='utf-8') as csvfile:
    fieldnames = ['first_name', 'last_name']

    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

    # ✅ code is now indented correctly
    writer.writeheader()
    writer.writerow({'first_name': 'Alice', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Bob', 'last_name': 'Smith'})

The with open() syntax takes care of automatically closing the file even if an exception is thrown.

Here is another example.

main.py

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file_name = 'example.txt'

with open(file_name, 'w', encoding='utf-8') as my_file:
    # ✅ code is indented correctly
    my_file.write('first line' + '\n')
    my_file.write('second line' + '\n')
    my_file.write('third line' + '\n')

Make sure you don't have code that tries to access the file after the with open() statement.

Any code that tries to access the file needs to be indented correctly.

Alternatively, you can store the file object into a variable and manually close it.

main.py

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file_name = 'example.txt'

my_file = open(file_name, 'w', encoding='utf-8')

my_file.write('first line' + '\n')
my_file.write('second line' + '\n')
my_file.write('third line' + '\n')

my_file.close() # 👈️  manually close file

Note that it's better to use the with open() syntax as it automatically closes the file after we are done.

You can use the closed property on a file object to check if it's closed or not.

main.py

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file_name = 'example.txt'

with open(file_name, 'w', encoding='utf-8') as my_file:
    # ✅ code is correctly indented
    my_file.write('first line' + '\n')
    my_file.write('second line' + '\n')
    my_file.write('third line' + '\n')

    print(my_file.closed)  # 👉️ False

print(my_file.closed)  # 👉️ True

The last line of code is not indented, so the file is already closed at that point.

Solve - ValueError: I/O operation on closed file in Python

Solve - ValueError: I/O operation on closed file in Python #

Borislav Hadzhiev