EC
csv.Error
PythonERRORCommonParsing

CSV parsing or writing error

Quick Answer

Wrap csv.reader() iteration in try/except csv.Error; use csv.field_size_limit() to raise the limit for large fields.

Production Risk

Medium — malformed CSV from external sources is common; always handle csv.Error in ETL pipelines.

What this means

Raised by the csv module when a parsing error occurs — typically a field that violates the dialect rules (e.g. an unterminated quoted field, or a line with more fields than the fieldnames in DictReader).

Why it happens
  1. 1Unterminated quoted field in the CSV data
  2. 2Field exceeds csv.field_size_limit() (default 131072 bytes)
  3. 3Binary data in a file opened in text mode with wrong encoding

Fix

Handle per-row and log bad lines

Handle per-row and log bad lines
import csv

with open('data.csv', newline='', encoding='utf-8') as f:
    reader = csv.DictReader(f)
    for i, row in enumerate(reader):
        try:
            process(row)
        except csv.Error as e:
            print(f'Line {reader.line_num}: {e}')

Why this works

reader.line_num gives the CSV line number (not the file line number) for accurate error reporting.

Code examples
Raise field size limitpython
import csv, sys
csv.field_size_limit(sys.maxsize)  # allow arbitrarily large fields
Detect encoding issuespython
# Always open CSV files with explicit encoding and newline='':
with open('f.csv', newline='', encoding='utf-8-sig') as f:
    reader = csv.reader(f)
Same error in other languages
ValueErrorin Python→
Sources
Official documentation ↗

Python Docs — csv module

Content generated with AI assistance and reviewed for accuracy. Found an error? hello@errcodes.dev

← All Python errors