title: openstack dashboard gives internal server error
body: <p>when i try to open dashboard it gives internal server error. It was running fine earlier but suddenly this error occurred.</p>
  
  <p>Here is my apache log :</p>
  
  <pre><code>[Fri Jun 23 16:43:50.321423 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599] mod_wsgi (pid=31878): Exception occurred processing WSGI script '/usr/share/openstack-dashboard/openstack_dashboard/wsgi/django.wsgi'.
  [Fri Jun 23 16:43:50.321468 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599] Traceback (most recent call last):
  [Fri Jun 23 16:43:50.321485 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/dist-packages/django/core/handlers/wsgi.py", line 168, in __call__
  [Fri Jun 23 16:43:50.321506 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     self.load_middleware()
  [Fri Jun 23 16:43:50.321607 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py", line 46, in load_middleware
  [Fri Jun 23 16:43:50.321620 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     mw_instance = mw_class()
  [Fri Jun 23 16:43:50.321625 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/dist-packages/django/middleware/locale.py", line 23, in __init__
  [Fri Jun 23 16:43:50.321633 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     for url_pattern in get_resolver(None).url_patterns:
  [Fri Jun 23 16:43:50.321637 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/dist-packages/django/core/urlresolvers.py", line 372, in url_patterns
  [Fri Jun 23 16:43:50.321644 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  [Fri Jun 23 16:43:50.321648 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/dist-packages/django/core/urlresolvers.py", line 366, in urlconf_module
  [Fri Jun 23 16:43:50.321654 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     self._urlconf_module = import_module(self.urlconf_name)
  [Fri Jun 23 16:43:50.321658 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
  [Fri Jun 23 16:43:50.321665 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     __import__(name)
  [Fri Jun 23 16:43:50.321669 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/urls.py", line 35, in &lt;module&gt;
  [Fri Jun 23 16:43:50.321676 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     url(r'^api/', include('openstack_dashboard.api.rest.urls')),
  [Fri Jun 23 16:43:50.321680 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/dist-packages/django/conf/urls/__init__.py", line 28, in include
  [Fri Jun 23 16:43:50.321687 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     urlconf_module = import_module(urlconf_module)
  [Fri Jun 23 16:43:50.321691 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
  [Fri Jun 23 16:43:50.321697 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     __import__(name)
  [Fri Jun 23 16:43:50.321701 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/api/__init__.py", line 34, in &lt;module&gt;
  [Fri Jun 23 16:43:50.321708 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599]     from openstack_dashboard.api import base
  [Fri Jun 23 16:43:50.321726 2017] [:error] [pid 31878:tid 140589128623872] [remote 10.0.30.11:41599] ImportError: cannot import name base
  </code></pre>