SeleniumHQ/selenium · error · ArgumentError

unknown option# : #

Error message

unknown option#{'s' if not_allowed.size != 1}: #{not_allowed.inspect}

What it means

Proxy.new iterates the options hash and only accepts keys present in the ALLOWED map (:type, :http, :no_proxy, :pac, :ssl, :auto_detect, :socks, :socks_username, :socks_password, :socks_version). Any unrecognized key is collected and, if any exist, ArgumentError is raised listing them. The message pluralizes to 'options' when more than one is rejected.

Solutions

1. Use only ALLOWED keys: :type, :http, :no_proxy, :pac, :ssl, :auto_detect, :socks, :socks_username, :socks_password, :socks_version.
2. Remove unrelated keys from the hash before passing it to Proxy.new.
3. Inspect Selenium::WebDriver::Proxy::ALLOWED to confirm valid key names.

Example fix

# before
proxy = Selenium::WebDriver::Proxy.new(ftp: 'proxy.example.com:8080')

# after
proxy = Selenium::WebDriver::Proxy.new(http: 'proxy.example.com:8080')

allowed = Selenium::WebDriver::Proxy::ALLOWED.keys
unknown = opts.keys - allowed
raise ArgumentError, "unknown proxy options: #{unknown.inspect}" unless unknown.empty?

def valid_proxy_opts?(opts)
  opts.is_a?(Hash) && (opts.keys - Selenium::WebDriver::Proxy::ALLOWED.keys).empty?
end

begin
  proxy = Selenium::WebDriver::Proxy.new(opts)
rescue ArgumentError => e
  raise unless e.message.include?('unknown option')
  allowed = Selenium::WebDriver::Proxy::ALLOWED.keys
  proxy = Selenium::WebDriver::Proxy.new(opts.slice(*allowed))
end

When it happens

Trigger: Calling Proxy.new(ftp: 'host:port') since ftp is not a supported key. A typo such as :htp or :ssl_proxy. Passing a generic capabilities hash that includes unrelated keys.

Common situations: Assuming an FTP proxy key exists. Copying keys from another library's proxy config. Merging an options hash that contains non-proxy entries.

Related errors

• invalid proxy type: #
• Cookie name cannot be null or empty
• could not convert # into color
• Custom page size must include :width and :height
• incompatible proxy type #

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/5603140b4982deaa. Report an issue: GitHub.

Appendix: source

Thrown at rb/lib/selenium/webdriver/common/proxy.rb:70

        end

        proxy
      end

      def initialize(opts = {})
        not_allowed = []

        opts.each do |k, v|
          if ALLOWED.key?(k)
            send(:"#{k}=", v)
          else
            not_allowed << k
          end
        end

        return if not_allowed.empty?

        raise ArgumentError, "unknown option#{'s' if not_allowed.size != 1}: #{not_allowed.inspect}"
      end

      def ==(other)
        other.is_a?(self.class) && as_json == other.as_json
      end
      alias eql? ==

      def http=(value)
        self.type = :manual
        @http = value
      end

      def no_proxy=(value)
        self.type = :manual
        @no_proxy = value
      end

      def ssl=(value)

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