I'm am cleaning up my random errors, and this one has me stumped. Should I build a custom error emailer that ignores these, or is it something django should fix? 
Internal Server Error: /join1/
Traceback (most recent call last):
  File "/home/exotic/.pyenv/versions/3.4.1/lib/python3.4/site-packages/django/core/handlers/base.py", line 87, in get_response
    response = middleware_method(request)
  File "/home/exotic/.pyenv/versions/3.4.1/lib/python3.4/site-packages/django/contrib/sessions/middleware.py", line 15, in process_request
    session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME, None)
  File "/home/exotic/.pyenv/versions/3.4.1/lib/python3.4/site-packages/django/utils/functional.py", line 55, in __get__
    res = instance.__dict__[self.func.__name__] = self.func(instance)
  File "/home/exotic/.pyenv/versions/3.4.1/lib/python3.4/site-packages/django/core/handlers/wsgi.py", line 143, in COOKIES
    raw_cookie = get_str_from_wsgi(self.environ, 'HTTP_COOKIE', '')
  File "/home/exotic/.pyenv/versions/3.4.1/lib/python3.4/site-packages/django/core/handlers/wsgi.py", line 262, in get_str_from_wsgi
    return value if six.PY2 else value.encode(ISO_8859_1).decode(UTF_8)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe7 in position 33: invalid continuation byte
Unparsed cookies. 
Request repr():
<WSGIRequest
path:/join1/,
GET:<QueryDict: {}>,
POST:<QueryDict: {}>,
COOKIES:<could not parse>,
META:{'CONTENT_LENGTH': '',
 'CONTENT_TYPE': '',
 'DOCUMENT_ROOT': '/usr/local/nginx/html',
 'HTTP_ACCEPT': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
 'HTTP_ACCEPT_ENCODING': 'gzip,deflate,sdch',
 'HTTP_ACCEPT_LANGUAGE': 'it-IT,it;q=0.8,en-US;q=0.6,en;q=0.4',
 'HTTP_CONNECTION': 'keep-alive',
 'HTTP_COOKIE': 'csrftoken=89uzZHmJ9ALZXxSTvVnEueCçWÈ\x03Ç\x9c(êh]Û\x8eÉ÷\x89&Æ/\x19á\x0f\t'
                '*£\x15Îè×MJ\x0e.1412634272',
. . . 
       
    
Your cookie content seems really garbage, it's unlikely that Django produced it.
Anyway, Django should not crash. I'll suggest a patch to fix this.