@@ -22,7 +22,7 @@ module Selenium
         class Common
           MAX_REDIRECTS   = 20 # same as chromium/gecko
           CONTENT_TYPE    = 'application/json'.freeze
-          DEFAULT_HEADERS = {'Accept' => CONTENT_TYPE}.freeze
+          DEFAULT_HEADERS = {'Accept' => CONTENT_TYPE, 'Content-Type' => 'application/x-www-form-urlencoded'}.freeze
 
           attr_accessor :timeout
           attr_writer :server_url
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module Selenium
  module WebDriver
    module Remote
      module Http
        class Common
          MAX_REDIRECTS   = 20 # same as chromium/gecko
          CONTENT_TYPE    = 'application/json'.freeze
          DEFAULT_HEADERS = {'Accept' => CONTENT_TYPE}.freeze

          attr_accessor :timeout
          attr_writer :server_url

          def initialize
            @timeout = nil
          end

          def quit_errors
            [IOError]
          end

          def close
            # hook for subclasses - will be called on Driver#quit
          end

          def call(verb, url, command_hash)
            url      = server_url.merge(url) unless url.is_a?(URI)
            headers  = DEFAULT_HEADERS.dup
            headers['Cache-Control'] = 'no-cache' if verb == :get

            if command_hash
              payload                   = JSON.generate(command_hash)
              headers['Content-Type']   = "#{CONTENT_TYPE}; charset=utf-8"
              headers['Content-Length'] = payload.bytesize.to_s if [:post, :put].include?(verb)

              WebDriver.logger.info("   >>> #{url} | #{payload}")
              WebDriver.logger.debug("     > #{headers.inspect}")
            elsif verb == :post
              payload = '{}'
              headers['Content-Length'] = '2'
            end

            request verb, url, headers, payload
          end

          private

          def server_url
            return @server_url if @server_url
            raise Error::WebDriverError, 'server_url not set'
          end

          def request(*)
            raise NotImplementedError, 'subclass responsibility'
          end

          def create_response(code, body, content_type)
            code = code.to_i
            body = body.to_s.strip
            content_type = content_type.to_s
            WebDriver.logger.info("<- #{body}")

            if content_type.include? CONTENT_TYPE
              raise Error::WebDriverError, "empty body: #{content_type.inspect} (#{code})\n#{body}" if body.empty?
              Response.new(code, JSON.parse(body))
            elsif code == 204
              Response.new(code)
            else
              msg = "unexpected response, code=#{code}, content-type=#{content_type.inspect}"
              msg << "\n#{body}" unless body.empty?

              raise Error::WebDriverError, msg
            end
          end
        end # Common
      end # Http
    end # Remote
  end # WebDriver
end # Selenium

Does it send requests with urlencoded bodies anywhere? I thought it sends only json. Maybe content-type should be `application/json` by default?