title: scrapy: ERROR: Error downloading <GET http://stackoverflow.com/questions?sort=votes> TypeError: 'float' object is not iterable
body: <p>I am a new learner of python and scrapy, I copy these codes from a video, they worked well in the video but when I have a try, there is a <strong>TypeError</strong> of   'float' object is not iterable, here are the codes</p>
  
  <pre><code>import scrapy
  
  class StackOverflowSpider(scrapy.Spider):
  name="stackoverflow"
  start_urls=["http://stackoverflow.com/questions?sort=votes"]
  
  def parse(self,response):
      for href in response.css('.question-summary h3 a::attr(href)'):
          full_url=response.urljoin(href.extract())
          yield scrapy.Request(full_url,callback=self.parse_question)
  
  def parse_question(self,response):
      yield {
          'title':response.css('h1 a::text').extract()[0],
          'votes':response.css(".question.vote-count-post::text").extract()[0],
          'body':response.css(".question.post-text").extract()[0],
          'tags':response.css(".question.post-tag::text").extract(),
          'link':response.url,
      }
  </code></pre>
  
  <p>then here is the Error:</p>
  
  <pre><code>2017-03-10 16:06:39 [scrapy] INFO: Enabled item pipelines:[]
  2017-03-10 16:06:39 [scrapy] INFO: Spider opened
  2017-03-10 16:06:39 [scrapy] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
  2017-03-10 16:06:39 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
  2017-03-10 16:06:40 [scrapy] ERROR: Error downloading &lt;GET http://stackoverflow.com/questions?sort=votes&gt;
  Traceback (most recent call last):
    File "C:\Anaconda2\lib\site-packages\twisted\internet\defer.py", line 1299, in _inlineCallbacks
      result = result.throwExceptionIntoGenerator(g)
    File "C:\Anaconda2\lib\site-packages\twisted\python\failure.py", line 393, in throwExceptionIntoGenerator
      return g.throw(self.type, self.value, self.tb)
    File "C:\Anaconda2\lib\site-packages\scrapy\core\downloader\middleware.py", line 43, in process_request
      defer.returnValue((yield download_func(request=request,spider=spider)))
    File "C:\Anaconda2\lib\site-packages\scrapy\utils\defer.py", line 45, in mustbe_deferred
      result = f(*args, **kw)
    File "C:\Anaconda2\lib\site-packages\scrapy\core\downloader\handlers\__init__.py", line 65, in download_request
      return handler.download_request(request, spider)
    File "C:\Anaconda2\lib\site-packages\scrapy\core\downloader\handlers\http11.py", line 60, in download_request
      return agent.download_request(request)
    File "C:\Anaconda2\lib\site-packages\scrapy\core\downloader\handlers\http11.py", line 285, in download_request
      method, to_bytes(url, encoding='ascii'), headers, bodyproducer)
    File "C:\Anaconda2\lib\site-packages\twisted\web\client.py", line 1631, in request
      parsedURI.originForm)
    File "C:\Anaconda2\lib\site-packages\twisted\web\client.py", line 1408, in _requestWithEndpoint
      d = self._pool.getConnection(key, endpoint)
    File "C:\Anaconda2\lib\site-packages\twisted\web\client.py", line 1294, in getConnection
      return self._newConnection(key, endpoint)
    File "C:\Anaconda2\lib\site-packages\twisted\web\client.py", line 1306, in _newConnection
      return endpoint.connect(factory)
    File "C:\Anaconda2\lib\site-packages\twisted\internet\endpoints.py", line 788, in connect
      EndpointReceiver, self._hostText, portNumber=self._port
    File "C:\Anaconda2\lib\site-packages\twisted\internet\_resolver.py", line 174, in resolveHostName
      onAddress = self._simpleResolver.getHostByName(hostName)
    File "C:\Anaconda2\lib\site-packages\scrapy\resolver.py", line 21, in getHostByName
      d = super(CachingThreadedResolver, self).getHostByName(name, timeout)
    File "C:\Anaconda2\lib\site-packages\twisted\internet\base.py", line 276, in getHostByName
      timeoutDelay = sum(timeout)
  TypeError: 'float' object is not iterable
  2017-03-10 16:06:40 [scrapy] INFO: Closing spider (finished)
  2017-03-10 16:06:40 [scrapy] INFO: Dumping Scrapy stats:
  {'downloader/exception_count': 1,
   'downloader/exception_type_count/exceptions.TypeError': 1,
   'downloader/request_bytes': 235,
   'downloader/request_count': 1,
   'downloader/request_method_count/GET': 1,
   'finish_reason': 'finished',
   'finish_time': datetime.datetime(2017, 3, 10, 8, 6, 40, 117000),
   'log_count/DEBUG': 1,
   'log_count/ERROR': 1,
   'log_count/INFO': 7,
   'scheduler/dequeued': 1,
   'scheduler/dequeued/memory': 1,
   'scheduler/enqueued': 1,
   'scheduler/enqueued/memory': 1,
   'start_time': datetime.datetime(2017, 3, 10, 8, 6, 39, 797000)}
  2017-03-10 16:06:40 [scrapy] INFO: Spider closed (finished)
  </code></pre>
  
  <p>thanks for your help!</p>