title: Flask Login: TypeError: decoding Unicode is not supported
body: <p>I am running flask, pymongo and flask-login as a stack.</p>
  
  <p>My flask app is running fine locally, but once I deploy it with uwsgi on nginx, I get a strange unicode error from flask_login extension.</p>
  
  <p><strong>In short:</strong></p>
  
  <pre><code>TypeError: decoding Unicode is not supported
  </code></pre>
  
  <p><strong>Traceback:</strong></p>
  
  <pre><code>[pid: 21753|app: 0|req: 5/5] 84.207.253.34 () {38 vars in 600 bytes} [Thu Jun 13 16:51:08 2013] GET / =&gt; generated 0 bytes in 4 msecs (HTTP/1.1 500) 0 headers in 0 bytes (0 switches on core 0)
  Traceback (most recent call last):
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
      return self.wsgi_app(environ, start_response)
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
      response = self.make_response(self.handle_exception(e))
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
      reraise(exc_type, exc_value, tb)
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
      response = self.full_dispatch_request()
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
      rv = self.handle_user_exception(e)
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
      reraise(exc_type, exc_value, tb)
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1473, in full_dispatch_request
      rv = self.preprocess_request()
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask/app.py", line 1666, in preprocess_request
      rv = func()
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask_login.py", line 311, in _load_user
      deleted = self._session_protection()
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask_login.py", line 325, in _session_protection
      ident = _create_identifier()
    File "/myproject/myproject-env/local/lib/python2.7/site-packages/flask_login.py", line 133, in _create_identifier
      request.headers.get("User-Agent")), 'utf8', errors='replace')
  TypeError: decoding Unicode is not supported
  </code></pre>
  
  <p>Why is this not happening in dev environment? Hence it must be somehow related to uwsgi on nginx.  Any suggestions? Many Thanks</p>