TypeError: can't serialize python objects

[idf]

After installing django-php-bridge, I am unable to serialize some python objects not related to auth into request's session:

Traceback (most recent call last):
  File "venv/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 223, in get_response
    response = middleware_method(request, response)
  File "venv/local/lib/python2.7/site-packages/django/contrib/sessions/middleware.py", line 49, in process_response
    request.session.save()
  File "venv/local/lib/python2.7/site-packages/django/contrib/sessions/backends/db.py", line 58, in save
    session_data=self.encode(self._get_session(no_load=must_create)),
  File "/third_party/django_php_bridge/backends/db.py", line 57, in encode
    return phpserialize.dumps(wrapped_session_dict)
  File "/venv/local/lib/python2.7/site-packages/phpserialize.py", line 411, in dumps
    return _serialize(data, False)
  File "venv/local/lib/python2.7/site-packages/phpserialize.py", line 396, in _serialize
    out.append(_serialize(value, False))
  File "venv/local/lib/python2.7/site-packages/phpserialize.py", line 409, in _serialize
    raise TypeError('can\'t serialize %r' % type(obj))
TypeError: can't serialize <class 'SomeClass'>

Can you help regarding this issue?