WarningCSV · .csv
CSV Mixed Delimiters — Inconsistent Column Separators
A CSV file that uses both commas and semicolons as delimiters across different rows, causing parsers to misalign columns.
Why It Fails
CSV parsers detect the delimiter from the first row and apply it uniformly. When rows use different delimiters, columns shift and data becomes corrupted. This often happens when merging CSV exports from different locales (US uses comma, EU uses semicolon).
Broken Example
name,age,city Alice,30,New York Bob;34;London Charlie,45,Tokyo
Expected Error Behavior
Parsers either split on the wrong character (producing too few or too many columns) or throw column count mismatch errors.
Affected Software
ExcelGoogle Sheetspandas read_csvPython csv moduleR read.csv
How to Fix
Standardize on a single delimiter. Use a script to detect and replace inconsistent delimiters before parsing.