csv.Error: line contains NULL byte Python error [Solved]

# Table of Contents

1. csv.Error: line contains NULL byte Python error
2. Creating a new file that doesn't contain NULL bytes
3. Try using the utf-16 encoding when opening the file
4. Skipping the rows with NULL Bytes

# csv.Error: line contains NULL byte Python error [Solved]

The Python "csv.Error: line contains NULL byte" occurs when your .csv file contains a NULL byte which commonly occurs when the file is saved with an incorrect encoding.

To solve the error, remove the NULL bytes from the .csv file.

You can use the following if statement to check if your file contains NULL bytes.

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if '\0' in open('employees.csv', newline='', encoding='utf-8').read():
    print('Your input file contains NULL bytes')
else:
    print('Your input file does NOT contain NULL bytes')

The code sample assumes that you have an employees.csv file in the same directory as your main.py script.

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first_name,last_name,date
Alice,Smith,01/21/1995 14:32:44.042010
Bobby,Hadz,04/14/1998 12:51:42.014000

The if block will run if your file contains NULL bytes.

To solve the error, try to remove the NULL bytes from the file.

For example, the following code sample:

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# 🔴 Before
import csv


with open('employees.csv', newline='', encoding='utf-8') as csvfile:
    csv_reader = csv.reader(csvfile, delimiter=',')

    for row in csv_reader:
        print(row)

Becomes the following code sample:

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# ✅ After
import csv


with open('employees.csv', newline='', encoding='utf-8') as csvfile:
    csv_reader = csv.reader(
        (row.replace('\0', '') for row in csvfile),
        delimiter=','
    )

    for row in csv_reader:
        print(row)

If the error persists, try to also remove the \x00 characters.

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import csv

with open('employees.csv', newline='', encoding='utf-8') as csvfile:
    csv_reader = csv.reader(
        (row.replace('\0', '').replace('\x00', '') for row in csvfile),
        delimiter=','
    )

    for row in csv_reader:
        print(row)

The str.replace() method returns a copy of the string with all occurrences of a substring replaced by the provided replacement.

The method takes the following parameters:

We used the method to remove all \0 and \x00 characters from the file.

# Creating a new file that doesn't contain NULL bytes

Alternatively, you can create a new file that doesn't contain NULL bytes.

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csv_file = open('employees.csv', 'rb')

data = csv_file.read().decode(encoding='utf-8')

csv_file.close()


# ✅ Create a new file without NULL bytes
output_csv_file = open('new-employees.csv', 'wb')

output_csv_file.write(
    bytes(data.replace('\0', '').replace('\x00', ''),
    encoding='utf-8')
)

output_csv_file.close()

We first open the file in rb (read binary) mode.

The next step is to read the file's contents and decode them to a Python string with the bytes.decode() method.

We then create a new .csv file and open it in wb (write binary) mode.

Once we remove all NULL bytes from the file, we write output to the file.

You would then use the new-employees.csv file and not the older employees.csv file that contains NULL bytes.

# Try using the utf-16 encoding when opening the file

You have to make sure to open the file with the same encoding in which it was saved.

Some commonly used encodings are utf-8, utf-16, utf-16-le, utf-16-be.

Here is an example of opening a file with the utf-16 encoding.

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import csv
import codecs


with codecs.open('employees.csv', 'rb', encoding='utf-16') as csvfile:
    csv_reader = csv.reader(csvfile, delimiter=',')

    for row in csv_reader:
        print(row)

Notice that the encoding keyword argument is set to utf-16.

This will only work if the file is encoded using the utf-16 encoding.

If you get an error, try using the utf-16-le, utf-16-be and utf-8 encodings.

# Skipping the rows with NULL Bytes

Alternatively, you can skip the rows that contain NULL bytes.

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import csv


with open('employees.csv', newline='', encoding='utf-8') as csvfile:
    csv_reader = csv.reader(
        csvfile,
        delimiter=','
    )

    while True:
        try:
            row = next(csv_reader)
            print(row)
        except csv.Error:
            continue
        except StopIteration:
            break

We used a while True loop to iterate over the rows in the CSV file.

On each iteration, we try to access the current row.

If a csv.Error exception is raised, we continue to the next iteration and skip the current row.

After the last row, a StopIteration exception is raised and is then handled by the except block.

Once a StopIteration is raised, we use the break statement to exit the while True loop.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Module 'csv' has no attribute 'reader' or 'writer' in Python
• How to escape commas in a CSV File [with Examples]
• Module 'lib' has no attribute 'X509_V_FLAG_CB_ISSUER_CHECK'
• _csv.Error: iterator should return strings, not bytes [Fix]
• Skip the header of a file with CSV Reader in Python
• How to read a CSV file from a URL using Python
• Python: Compare two CSV files and print the differences