signed_cookies and PickleSerializer seems incompatible.

[Drife59]

If you do the setup as following (I know it is not recommended for security reason):

SESSION_ENGINE = 'django.contrib.sessions.backends.signed_cookies'
SESSION_SERIALIZER = 'django.contrib.sessions.serializers.PickleSerializer'

It basically breaks render of template.

Here is the full stacktrace:

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/base.py", line 170, in _get_session

return self._session_cache

AttributeError: 'SessionStore' object has no attribute '_session_cache'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "/usr/local/lib/python3.4/dist-packages/django/core/handlers/base.py", line 111, in get_response

response = wrapped_callback(request, *callback_args, callback_kwargs)

File "<path>/views.py", line 266, in <your View>

if request.user.is_authenticated():

File "/usr/local/lib/python3.4/dist-packages/django/utils/functional.py", line 224, in inner

self._setup()

File "/usr/local/lib/python3.4/dist-packages/django/utils/functional.py", line 357, in _setup

self._wrapped = self._setupfunc()

File "/usr/local/lib/python3.4/dist-packages/django/contrib/auth/middleware.py", line 22, in <lambda>

request.user = SimpleLazyObject(lambda: get_user(request))

File "/usr/local/lib/python3.4/dist-packages/django/contrib/auth/middleware.py", line 10, in get_user

request._cached_user = auth.get_user(request)

File "/usr/local/lib/python3.4/dist-packages/django/contrib/auth/init.py", line 152, in get_user

user_id = request.session[SESSION_KEY]

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/base.py", line 49, in getitem

return self._session[key]

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/base.py", line 175, in _get_session

self._session_cache = self.load()

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/signed_cookies.py", line 20, in load

salt='django.contrib.sessions.backends.signed_cookies')

File "/usr/local/lib/python3.4/dist-packages/django/core/signing.py", line 145, in loads

return serializer().loads(data)

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/serializers.py", line 17, in loads

return pickle.loads(data)

_pickle.UnpicklingError: invalid load key, '{'.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/base.py", line 170, in _get_session

return self._session_cache

AttributeError: 'SessionStore' object has no attribute '_session_cache'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "/usr/lib/python3.4/wsgiref/handlers.py", line 137, in run

self.result = application(self.environ, self.start_response)

File "/usr/local/lib/python3.4/dist-packages/django/contrib/staticfiles/handlers.py", line 64, in call

return self.application(environ, start_response)

File "/usr/local/lib/python3.4/dist-packages/django/core/handlers/wsgi.py", line 187, in call

response = self.get_response(request)

File "/usr/local/lib/python3.4/dist-packages/django/core/handlers/base.py", line 199, in get_response

response = self.handle_uncaught_exception(request, resolver, sys.exc_info())

File "/usr/local/lib/python3.4/dist-packages/django/core/handlers/base.py", line 236, in handle_uncaught_exception

return debug.technical_500_response(request, *exc_info)

File "/usr/local/lib/python3.4/dist-packages/django/views/debug.py", line 91, in technical_500_response

html = reporter.get_traceback_html()

File "/usr/local/lib/python3.4/dist-packages/django/views/debug.py", line 349, in get_traceback_html

c = Context(self.get_traceback_data(), use_l10n=False)

File "/usr/local/lib/python3.4/dist-packages/django/views/debug.py", line 307, in get_traceback_data

frames = self.get_traceback_frames()

File "/usr/local/lib/python3.4/dist-packages/django/views/debug.py", line 465, in get_traceback_frames

'vars': self.filter.get_traceback_frame_variables(self.request, tb.tb_frame),

File "/usr/local/lib/python3.4/dist-packages/django/views/debug.py", line 232, in get_traceback_frame_variables

cleansed[name] = self.cleanse_special_types(request, value)

File "/usr/local/lib/python3.4/dist-packages/django/views/debug.py", line 187, in cleanse_special_types

if isinstance(value, HttpRequest):

File "/usr/local/lib/python3.4/dist-packages/django/utils/functional.py", line 224, in inner

self._setup()

File "/usr/local/lib/python3.4/dist-packages/django/utils/functional.py", line 357, in _setup

self._wrapped = self._setupfunc()

File "/usr/local/lib/python3.4/dist-packages/django/contrib/auth/middleware.py", line 22, in <lambda>

request.user = SimpleLazyObject(lambda: get_user(request))

File "/usr/local/lib/python3.4/dist-packages/django/contrib/auth/middleware.py", line 10, in get_user

request._cached_user = auth.get_user(request)

File "/usr/local/lib/python3.4/dist-packages/django/contrib/auth/init.py", line 152, in get_user

user_id = request.session[SESSION_KEY]

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/base.py", line 49, in getitem

return self._session[key]

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/base.py", line 175, in _get_session

self._session_cache = self.load()

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/backends/signed_cookies.py", line 20, in load

salt='django.contrib.sessions.backends.signed_cookies')

File "/usr/local/lib/python3.4/dist-packages/django/core/signing.py", line 145, in loads

return serializer().loads(data)

File "/usr/local/lib/python3.4/dist-packages/django/contrib/sessions/serializers.py", line 17, in loads

return pickle.loads(data)

_pickle.UnpicklingError: invalid load key, '{'.

Of course replace " File "<path>/views.py", line 266, in <your View>" with your view.
I tried different views and same result each time.

Seems we cannot properly access to the session, for managing user.

I found no workaround but to use a different serializer or session engine.