scrapy domz报错TypeError: 'float' object is not iterable

问题：

[scrapy] ERROR: Error downloading

GET http://www.dmoz.org/robots.txt: ‘float’ object is not iterable

Traceback (most recent call last):

File “d:\Anaconda3\lib\site-packages\twisted\internet\defer.py”, line 1299, in _inlineCallbacks

result = result.throwExceptionIntoGenerator(g)

File “d:\Anaconda3\lib\site-packages\twisted\python\failure.py”, line 393, in throwExceptionIntoGenerator

return g.throw(self.type, self.value, self.tb)

File “d:\Anaconda3\lib\site-packages\scrapy\core\downloader\middleware.py”, line 43, in process_request

defer.returnValue((yield download_func(request=request,spider=spider)))

File “d:\Anaconda3\lib\site-packages\scrapy\utils\defer.py”, line 45, in mustbe_deferred

result = f(*args, **kw)

…

scrapy与twisted版本不兼容。见https://github.com/scrapy/scrapy/issues/2606