SeleniumHQ/selenium · error · Error::UnsupportedOperationError

you may only select all options of a multi-select

Error message

you may only select all options of a multi-select

What it means

Support::Select#select_all iterates every option and selects it, which is only meaningful for a <select multiple>. On a single-select calling select_all is a logic error, so the binding raises Error::UnsupportedOperationError before touching the DOM.

Source

Thrown at rb/lib/selenium/webdriver/support/select.rb:144

          when :text
            deselect_by_text what
          when :value
            deselect_by_value what
          when :index
            deselect_by_index what
          else
            raise ArgumentError, "can't deselect options by #{how.inspect}"
          end
        end

        #
        # Select all unselected options. Only valid if the element supports multiple selections.
        #
        # @raise [Error::UnsupportedOperationError] if the element does not support multiple selections.
        #

        def select_all
          raise Error::UnsupportedOperationError, 'you may only select all options of a multi-select' unless multiple?

          options.each { |e| select_option e }
        end

        #
        # Deselect all selected options. Only valid if the element supports multiple selections.
        #
        # @raise [Error::UnsupportedOperationError] if the element does not support multiple selections.
        #

        def deselect_all
          raise Error::UnsupportedOperationError, 'you may only deselect all options of a multi-select' unless multiple?

          options.each { |e| deselect_option e }
        end

        private

View on GitHub (pinned to aa36b38e69)

Solutions

1. Guard with select.multiple? before calling select_all.
2. Confirm the <select> has the 'multiple' attribute in HTML.
3. For single-selects, use select_by(:text/:index/:value) instead of select_all.

Example fix

# before
select.select_all

# after
if select.multiple?
  select.select_all
else
  select.select_by(:index, 0)
end

select.select_all if select.multiple?

def multi_select?(select)
  select.multiple?
end

begin
  select.select_all
rescue Selenium::WebDriver::Error::UnsupportedOperationError
  select.select_by(:index, 0) # fallback for single-select
end

When it happens

Trigger: Calling select.select_all when the underlying <select> does not have the 'multiple' attribute (i.e. select.multiple? is false).

Common situations: A generic helper that always calls select_all regardless of select type; the page changed a multi-select to a single-select; locator matched the wrong select element.

Related errors

• you may only deselect all options of a multi-select
• you may only deselect option of a multi-select
• Full Page Screenshots are not supported for #{inspect}
• unexpected tag name #{tag_name.inspect}
• no options are selected

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/64f53ba455234baf. Report an issue: GitHub.