Can everybody help me the follow error?

what should I do??

============================================================= Exception happened during processing of request from ('192.168.1.38', 56426)

Traceback (most recent call last):

File "/usr/lib/python2.7/SocketServer.py", line 582, in process_request_thread

self.finish_request(request, client_address)

File "/usr/lib/python2.7/SocketServer.py", line 323, in finish_request

self.RequestHandlerClass(request, client_address, self)

File "/usr/lib/python2.7/SocketServer.py", line 638, in __init__

self.handle()

File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 189, in handle

return rv

UnboundLocalError: local variable 'rv' referenced before assignment