SeleniumHQ/selenium · error · ArgumentError

Valid types are :tab and :window, received: #{type.inspect}

Error message

Valid types are :tab and :window, received: #{type.inspect}

What it means

Raised by TargetLocator#new_window when the type argument is not one of :window or :tab. These are the only two valid new-window types per the W3C WebDriver specification. The check uses include? on [:window, :tab], so strings, integers, or other symbols all fail.

Source

Thrown at rb/lib/selenium/webdriver/common/target_locator.rb:55

      end

      #
      # switch to the parent frame
      #

      def parent_frame
        @bridge.switch_to_parent_frame
      end

      #
      # Switch to a new top-level browsing context
      #
      # @param type either :tab or :window
      #

      # steep:ignore:start
      def new_window(type = :window)
        raise ArgumentError, "Valid types are :tab and :window, received: #{type.inspect}" unless %i[window
                                                                                                     tab].include?(type)

        handle = @bridge.new_window(type)['handle']

        if block_given?
          execute_and_close = proc do
            yield(self)
            begin
              @bridge.close
            rescue Error::NoSuchWindowError
              # window already closed
            end
          end
          window(handle, &execute_and_close)
        else
          window(handle)
        end
      end

View on GitHub (pinned to aa36b38e69)

Solutions

1. Pass :window or :tab exactly (lowercase symbols).
2. If accepting type from config/user input, normalize it: type.to_sym and validate against [:window, :tab].

Example fix

// before
handle = driver.switch_to.new_window(:popup)  # invalid
handle = driver.switch_to.new_window('window')   # string, not symbol

// after
handle = driver.switch_to.new_window(:window)
handle = driver.switch_to.new_window(:tab)

VALID_WINDOW_TYPES = %i[window tab].freeze

def safe_new_window(driver, type = :window)
  type = type.to_sym
  raise ArgumentError, "Invalid window type: #{type}. Use :window or :tab." unless VALID_WINDOW_TYPES.include?(type)
  driver.switch_to.new_window(type)
end

def valid_window_type?(type)
  %i[window tab].include?(type.to_sym)
end

begin
  handle = driver.switch_to.new_window(type)
rescue ArgumentError => e
  raise unless e.message.include?('Valid types are')
  raise ArgumentError, "new_window type must be :window or :tab, got #{type.inspect}"
end

When it happens

Trigger: Calling driver.switch_to.new_window(:popup). Calling driver.switch_to.new_window('window') with a string. Calling driver.switch_to.new_window(:Window) (capitalized). Passing a variable that is nil or an unexpected symbol.

Common situations: Using a non-standard window type name. Passing a string from config instead of a symbol. Case sensitivity mistakes (:Window vs :window). Expecting :popup or :new to work.

Related errors

• incompatible proxy type #{type.inspect} (already set to #{@t
• cannot find element by #{how.inspect}
• cannot find elements by #{how.inspect}
• expected #{arg.inspect}:#{arg.class} to respond to #shift
• expected #{arr.inspect} to have 2 elements

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/a794de1a3821e35f. Report an issue: GitHub.