pola-rs/polars · error · ParameterCollisionError

cannot specify both `columns` and `read_options["use_columns

Error message

cannot specify both `columns` and `read_options["use_columns"]`

What it means

polars.exceptions.ParameterCollisionError raised while normalizing read_excel options for the calamine engine. The top-level columns parameter and the engine-level read_options['use_columns'] both select which columns to load; supplying both would make precedence ambiguous, so polars rejects the combination during option normalization, before parsing starts.

Source

Thrown at py-polars/src/polars/io/spreadsheet/functions.py:740

        return parsed_sheets
    return next(iter(parsed_sheets.values()))


def _get_read_options(
    read_options: dict[str, Any] | None,
    *,
    engine: ExcelSpreadsheetEngine,
    columns: Sequence[int] | Sequence[str] | None,
    infer_schema_length: int | None,
    has_header: bool,
) -> dict[str, Any]:
    """Normalise top-level parameters to engine-specific 'read_options' dict."""
    read_options = (read_options or {}).copy()

    if engine == "calamine":
        if ("use_columns" in read_options) and columns:
            msg = 'cannot specify both `columns` and `read_options["use_columns"]`'
            raise ParameterCollisionError(msg)
        elif read_options.get("header_row") is not None and has_header is False:
            msg = 'the values of `has_header` and `read_options["header_row"]` are not compatible'
            raise ParameterCollisionError(msg)
        elif ("schema_sample_rows" in read_options) and (
            infer_schema_length != N_INFER_DEFAULT
        ):
            msg = 'cannot specify both `infer_schema_length` and `read_options["schema_sample_rows"]`'
            raise ParameterCollisionError(msg)

        read_options["schema_sample_rows"] = infer_schema_length
        if has_header is False and "header_row" not in read_options:
            read_options["header_row"] = None

    elif engine == "xlsx2csv":
        if ("columns" in read_options) and columns:
            msg = 'cannot specify both `columns` and `read_options["columns"]`'
            raise ParameterCollisionError(msg)
        elif (

View on GitHub (pinned to df599052da)

Solutions

1. Keep the top-level parameter: pl.read_excel(..., columns=['A', 'B']) and delete 'use_columns' from read_options.
2. Or keep it engine-level: pass read_options={'use_columns': [0, 1]} and drop columns — useful when the same read_options dict is reused with the raw calamine reader.
3. In wrappers, pop one of the two before delegating to read_excel.

Example fix

# before
pl.read_excel('f.xlsx', columns=['a', 'b'], read_options={'use_columns': [0, 1]})

# after
pl.read_excel('f.xlsx', columns=['a', 'b'])

if engine == 'calamine':
    if columns and 'use_columns' in (read_options or {}):
        (read_options or {}).pop('use_columns')  # keep the top-level param
pl.read_excel(path, engine=engine, columns=columns, read_options=read_options)

try:
    pl.read_excel(path, columns=columns, read_options=read_options)
except pl.exceptions.ParameterCollisionError as e:
    if 'use_columns' in str(e):
        ro = {k: v for k, v in (read_options or {}).items() if k != 'use_columns'}
        pl.read_excel(path, columns=columns, read_options=ro)
    else:
        raise

When it happens

Trigger: pl.read_excel('f.xlsx', engine='calamine', columns=['A', 'B'], read_options={'use_columns': [0, 1]}). Any truthy columns together with a 'use_columns' key present in read_options.

Common situations: Migrating calamine (python-calamine) example code that used use_columns into polars' read_excel while keeping the polars-style columns argument; teams mixing both styles in shared helper functions.

Related errors

• the values of `has_header` and `read_options["header_row"]`
• cannot specify both `infer_schema_length` and `read_options[
• no workbook found at path {src!r}
• no data found in the given workbook(s) and sheet(s)
• no matching sheets found when `sheet_{param}` is {value!r}

AI-assisted analysis of pola-rs/polars@df599052da (2026-08-16). Data as JSON: /api/errors/a7a83a62896ed6df. Report an issue: GitHub.