pola-rs/polars · error · NoDataError

no data found in the given workbook(s) and sheet(s)

Error message

no data found in the given workbook(s) and sheet(s)

What it means

polars.exceptions.NoDataError raised by _unpack_read_results after reading Excel sources: the read completed but produced zero DataFrames. This happens when every selected sheet parsed to nothing — e.g. sheets whose rows were all dropped by drop_empty_rows/drop_empty_cols — so there is no frame to return or concatenate.

Source

Thrown at py-polars/src/polars/io/spreadsheet/functions.py:99

                src = str(src)
            sources.append(src)

    return sources, read_multiple_workbooks


def _standardize_duplicates(s: str) -> str:
    """Standardize columns with '_duplicated_n' names."""
    return re.sub(r"_duplicated_(\d+)", repl=r"\1", string=s)


def _unpack_read_results(
    frames: list[pl.DataFrame] | list[dict[str, pl.DataFrame]],
    *,
    read_multiple_workbooks: bool,
) -> Any:
    if not frames:
        msg = "no data found in the given workbook(s) and sheet(s)"
        raise NoDataError(msg)

    if not read_multiple_workbooks:
        # one sheet from one workbook
        return frames[0]

    if isinstance(frames[0], pl.DataFrame):
        # one sheet from multiple workbooks
        return concat(frames, how="vertical_relaxed")  # type: ignore[type-var]
    else:
        # multiple sheets from multiple workbooks
        sheet_frames = defaultdict(list)
        for res in frames:
            for sheet, df in res.items():  # type: ignore[union-attr]
                sheet_frames[sheet].append(df)
        return {k: concat(v, how="vertical_relaxed") for k, v in sheet_frames.items()}


@overload

View on GitHub (pinned to df599052da)

Solutions

1. Inspect the workbook and confirm the target sheet actually contains data (check it in Excel/another reader).
2. Handle the empty case explicitly: wrap in try/except NoDataError and substitute an explicit empty schema or skip processing, rather than letting the exception kill the job.
3. Tighten glob patterns or sheet selection (sheet_name/sheet_id) so blank placeholder sheets are not read.
4. If blank-looking rows matter, revisit drop_empty_rows=False / raise_if_empty-style handling.

Example fix

# before
df = pl.read_excel('report.xlsx')  # NoDataError when sheet is blank

# after
try:
    df = pl.read_excel('report.xlsx')
except pl.exceptions.NoDataError:
    df = pl.DataFrame(schema={'date': pl.Date, 'amount': pl.Float64})  # explicit empty result

# Optional pre-check that the target sheet has any non-empty cells (needs openpyxl):
from openpyxl import load_workbook
wb = load_workbook(path, read_only=True)
has_any = any(cell.value is not None for row in wb[sheet].iter_rows() for cell in row)
if not has_any:
    df = pl.DataFrame(schema=expected_schema)  # skip the read
else:
    df = pl.read_excel(path, sheet_name=sheet)

try:
    df = pl.read_excel(path, sheet_name=sheet)
except pl.exceptions.NoDataError:
    df = pl.DataFrame(schema=expected_schema)  # explicit, typed empty result
    log.warning('workbook %s sheet %s contained no data', path, sheet)

When it happens

Trigger: pl.read_excel('empty.xlsx') where the sheet has only blank rows and drop_empty_rows=True (default); reading multiple workbooks via glob where every matched file is empty; sheet combinations that select only blank sheets.

Common situations: Scheduled jobs reading a periodically-generated report that is occasionally empty; templates with header-only or whitespace-only sheets; glob patterns matching both data files and blank placeholder files.

Related errors

• no workbook found at path {src!r}
• no matching sheets found when `sheet_{param}` is {value!r}
• cannot specify both `columns` and `read_options["use_columns
• the values of `has_header` and `read_options["header_row"]`
• cannot specify both `infer_schema_length` and `read_options[

AI-assisted analysis of pola-rs/polars@df599052da (2026-08-16). Data as JSON: /api/errors/01503a5877f486ed. Report an issue: GitHub.