SeleniumHQ/selenium · error · NotImplementedError

You may only deselect options of a multi-select

Error message

You may only deselect options of a multi-select

What it means

`deselect_by_value()` only operates on multi-selects. On a single-select it raises `NotImplementedError('You may only deselect options of a multi-select')` before doing any work, because deselect semantics are invalid for single-select elements.

Source

Thrown at py/selenium/webdriver/support/select.py:174

        for opt in self.options:
            self._unset_selected(opt)

    def deselect_by_value(self, value: str) -> None:
        """Deselect all options that have a value matching the argument.

        Example:
            When given "foo" this would deselect an option like:

                `<option value="foo">Bar</option>`

        Args:
            value: The value to match against

        Raises:
            NoSuchElementException: If there is no option with specified value in SELECT
        """
        if not self.is_multiple:
            raise NotImplementedError("You may only deselect options of a multi-select")
        matched = False
        css = f"option[value = {self._escape_string(value)}]"
        opts = self._el.find_elements(By.CSS_SELECTOR, css)
        for opt in opts:
            self._unset_selected(opt)
            matched = True
        if not matched:
            raise NoSuchElementException(f"Could not locate element with value: {value}")

    def deselect_by_index(self, index: int) -> None:
        """Deselect the option at the given index by examining the "index" attribute.

        Args:
            index: The option at this index will be deselected

        Raises:
            NoSuchElementException: If there is no option with specified index in SELECT
        """

View on GitHub (pinned to aa36b38e69)

Solutions

1. Guard with `if select.is_multiple:` before calling
2. For single-selects, change selection rather than deselect
3. Catch NotImplementedError to branch on select type

Example fix

// before
select.deselect_by_value("foo")

// after
if select.is_multiple:
    select.deselect_by_value("foo")

if select.is_multiple:
    select.deselect_by_value(value)

def is_multi(select_obj) -> bool:
    return bool(select_obj.is_multiple)

When it happens

Trigger: Calling `select.deselect_by_value('foo')` when the wrapped select lacks `multiple` (so `is_multiple` is False). The very first guard raises.

Common situations: Shared utility code run against heterogeneous selects; assuming a select is multiple when it is not; form schema changed and a formerly-multi select became single.

Related errors

• You may only deselect all options of a multi-select
• Could not locate element with value: {value}
• You may only deselect all options of a multi-select
• You may only deselect options of a multi-select
• Select only works on <select> elements, not on {webelement.t

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/803eb71195e11086. Report an issue: GitHub.