Exception Value: 'NoneType' object has no attribute 'year'

[aloptrbl]

Environment:

Request Method: GET
Request URL: http://127.0.0.1:8000/dashboard/

Django Version: 1.11.20
Python Version: 2.7.16
Installed Applications:
('django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'cbd')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'django.middleware.security.SecurityMiddleware')

Traceback:

File "C:\Python27\lib\site-packages\django\core\handlers\exception.py" in inner
41. response = get_response(request)

File "C:\Python27\lib\site-packages\django\core\handlers\base.py" in _legacy_get_response
249. response = self._get_response(request)

File "C:\Python27\lib\site-packages\django\core\handlers\base.py" in _get_response
187. response = self.process_exception_by_middleware(e, request)

File "C:\Python27\lib\site-packages\django\core\handlers\base.py" in _get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "C:\Python27\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
23. return view_func(request, *args, **kwargs)

File "C:\xampp\htdocs\cbd\cbd_project\cbd\views.py" in dashboard
145. sales_by_month_ts = qss.time_series(start, end, interval='months')

File "C:\Python27\lib\site-packages\qsstats_init_.py" in time_series
70. return self._fast_time_series(*(args+[engine]))

File "C:\Python27\lib\site-packages\qsstats_init_.py" in _fast_time_series
106. start, _ = get_bounds(start, interval.rstrip('s'))

File "C:\Python27\lib\site-packages\qsstats\utils.py" in get_bounds
28. day = _to_datetime(_remove_time(dt))

File "C:\Python27\lib\site-packages\qsstats\utils.py" in _remove_time
9. return datetime.datetime(dt.year, dt.month, dt.day, tzinfo=tzinfo)

Exception Type: AttributeError at /dashboard/
Exception Value: 'NoneType' object has no attribute 'year'

is this because of outdated package?