使用tornado开发的商城，查看后台的打印信息时不时会看到这样的报错信息：

[E 160213 11:44:39 http1connection:54] Uncaught exception
8032 Traceback (most recent call last):
8033 File "/usr/local/lib/python3.4/dist-packages/tornado/http1connection.py", line 238, in _read_message
8034 delegate.finish()
8035 File "/usr/local/lib/python3.4/dist-packages/tornado/httpserver.py", line 290, in finish
8036 self.delegate.finish()
8037 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 1984, in finish
8038 self.execute()
8039 File "/usr/local/lib/python3.4/dist-packages/blueware-1.0.10/blueware/hooks/framework_tornado/web.py", line 480, in _bw_wrapper__RequestDispatcher_execute
8040 future = wrapped(args, *kwargs)
8041 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 2004, in execute
8042 **self.handler_kwargs)
8043 File "/usr/local/lib/python3.4/dist-packages/blueware-1.0.10/blueware/hooks/framework_tornado/web.py", line 448, in bw_wrapper_RequestHandler___init__
8044 return wrapped(args, *kwargs)
8045 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 185, in init
8046 self.initialize(**kwargs)
8047 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 2718, in wrapper
8048 self.redirect(url)
8049 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 671, in redirect
8050 self.finish()
8051 File "/usr/local/lib/python3.4/dist-packages/blueware-1.0.10/blueware/hooks/framework_tornado/web.py", line 309, in bw_wrapper_RequestHandler_finish
8052 return wrapped(args, *kwargs)
8053 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 934, in finish
8054 self.flush(include_footers=True)
8055 File "/usr/local/lib/python3.4/dist-packages/tornado/web.py", line 870, in flush
8056 for transform in self._transforms:
8057 TypeError: 'NoneType' object is not iterable

请问有谁遇到过类似的问题或者知道是什么原因呢，多谢指教～～