pandas-dev/pandas · error · ValueError

Must provide an even number of non-keyword arguments

Error message

Must provide an even number of non-keyword arguments

What it means

Raised by set_option (config.py:273-275) when called with zero or an odd number of positional arguments, since options must be supplied as (pattern, value) pairs. The single-dict form is handled before this check.

Source

Thrown at pandas/_config/config.py:275

    Dictionary Input:

    >>> pd.set_option({"display.max_columns": 4, "display.precision": 1})
    >>> df = pd.DataFrame([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]])
    >>> df
    0  1  ...  3   4
    0  1  2  ...  4   5
    1  6  7  ...  9  10
    [2 rows x 5 columns]
    >>> pd.reset_option("display.max_columns")
    >>> pd.reset_option("display.precision")
    """
    # Handle dictionary input
    if len(args) == 1 and isinstance(args[0], dict):
        args = tuple(kv for item in args[0].items() for kv in item)

    nargs = len(args)
    if not nargs or nargs % 2 != 0:
        raise ValueError("Must provide an even number of non-keyword arguments")

    for k, v in zip(args[::2], args[1::2], strict=True):
        key = _get_single_key(k)

        opt = _get_registered_option(key)
        if opt and opt.validator:
            opt.validator(v)

        # walk the nested dict
        root, k_root = _get_root(key)
        root[k_root] = v

        if opt is not None and opt.cb:
            opt.cb(key)


def describe_option(pat: str = "", _print_desc: bool = True) -> str | None:
    """

View on GitHub (pinned to 71959b8cb9)

Solutions

1. Supply arguments in pairs: pd.set_option('a', 1, 'b', 2).
2. Pass a single dict: pd.set_option({'display.max_columns': 4, 'display.precision': 1}).
3. Double-check argument count in dynamically built *args before calling set_option.

Example fix

# before
pd.set_option('display.max_columns', 'display.precision', 2)  # 3 args

# after
pd.set_option('display.max_columns', 10, 'display.precision', 2)

def safe_set_option(*args):
    assert len(args) >= 2 and len(args) % 2 == 0, 'need (pat, val) pairs'
    pd.set_option(*args)

When it happens

Trigger: pd.set_option('display.max_columns') (1 arg) or pd.set_option('a', 1, 'b') (3 args), or accidentally passing a dict inside a tuple.

Common situations: Missing the value argument, trailing comma in a multi-option call, or refactoring that drops a value.

Related errors

• Provide an even amount of arguments as option_context(pat, v
• Value must be an instance of {type_repr}
• Value must be one of {pp_values}
• Value must be a nonnegative integer or None
• Value must be a callable

AI-assisted analysis of pandas-dev/pandas@71959b8cb9 (2026-08-07). Data as JSON: /api/errors/93326b4d4a5ba963. Report an issue: GitHub.