pandas-dev/pandas · error · ValueError

Value must be one of {pp_values}

Error message

Value must be one of {pp_values}

What it means

Raised by the is_one_of_factory validator, which restricts a config option to a fixed list of legal values (optionally plus callables). When set_option() is called with a value not in the legal set, it raises ValueError listing the allowed values. The shipped usage is io/pytables.py:235 registering the format option with legal values ['fixed', 'table', None].

Source

Thrown at pandas/_config/config.py:902

        if not isinstance(x, _type):
            raise ValueError(f"Value must be an instance of {type_repr}")

    return inner


def is_one_of_factory(legal_values: Sequence) -> Callable[[Any], None]:
    callables = [c for c in legal_values if callable(c)]
    legal_values = [c for c in legal_values if not callable(c)]

    def inner(x: object) -> None:
        if x not in legal_values:
            if not any(c(x) for c in callables):
                uvals = [str(lval) for lval in legal_values]
                pp_values = "|".join(uvals)
                msg = f"Value must be one of {pp_values}"
                if len(callables):
                    msg += " or a callable"
                raise ValueError(msg)

    return inner


def is_nonnegative_int(value: object) -> None:
    """
    Verify that value is None or a positive int.

    Parameters
    ----------
    value : None or int
            The `value` to be checked.

    Raises
    ------
    ValueError
        When the value is not None or is a negative integer
    """

View on GitHub (pinned to 71959b8cb9)

Solutions

1. Use one of the legal values listed in the error message — for HDF format that is 'fixed', 'table', or None.
2. Run pd.describe_option('io.hdf.table.format') to see the allowed values before setting.
3. If writing your own option, re-read the legal_values list you passed to is_one_of_factory.

Example fix

# before
pd.set_option('io.hdf.table.format', 'csv')

# after
pd.set_option('io.hdf.table.format', 'table')

legal = ['fixed', 'table', None]
value = get_format()
if value not in legal:
    raise ValueError(f'format must be one of {legal}, got {value!r}')
pd.set_option('io.hdf.table.format', value)

When it happens

Trigger: Calling pd.set_option('io.hdf.table.format', value) with anything other than 'fixed', 'table', or None triggers the check (the HDF5 format option). Registering a custom option with validator=cf.is_one_of_factory([...]) and setting an out-of-set value does the same.

Common situations: Typing a format string (e.g. 'csv' or 'parquet') that isn't a valid HDF format; passing a value from an unvalidated config file; confusion about whether None is a valid sentinel.

Related errors

• Value must be an instance of {type_repr}
• Value must be a nonnegative integer or None
• Value must be a callable
• No such keys(s): {pat!r}
• Must provide an even number of non-keyword arguments

AI-assisted analysis of pandas-dev/pandas@71959b8cb9 (2026-08-07). Data as JSON: /api/errors/05dc41ffdbfd83c9. Report an issue: GitHub.