Setting request.session causes HTTP 500 Error when posting form to Django -

even setting session simple string changes http response status 200 500. httml button has id="requestquote". webpage javascript:

$('#requestquote').click(function(){     var jpicks = json.stringify(picks);     $.post("requestforquote",{counties:jpicks}).done(function(){         window.location = base_url + "countyparcels/quoteform"     }); }); 

url.py

urlpatterns = [     url(r'^(requestforquote)$',views.request4quote),     url(r'^(quoteform)$',views.quoteform) ] 

views.py

shopping_cart = 'shoppingcart'  @csrf_exempt def request4quote(request,misc):     try:         request.session[shopping_cart] = request.post['counties']  # no    exception here     except exception e:         print e.message     try:         response = httpresponse("true",content_type="text/plain")  # no exception here     except exception e:         print e.message         response = http404     return response  # http: 500  if include session setting code above         # error session set simple string literal ... "true" 

the error occurring in response variable value.
returning http404 type object in exception, raise attributeerror, it's exception leading exception.

from code provided above thing can think of didn't import httpresponse.
need : from django.http import httpresponse

if doesn't work ll need provide traceback.