title: ContentType doesn't declare an explicit app_label
body: <p>I am deploying a Django 1.10 project onto an Ubuntu server with Apache and mod_wsgi. I am getting the following 500 error which I can't solve:</p>
  
  <blockquote>
    <p>RuntimeError: Model class
    django.contrib.contenttypes.models.ContentType doesn't declare an
    explicit app_label and isn't in an application in INSTALLED_APPS.</p>
  </blockquote>
  
  <p>installed_apps in settings.py:</p>
  
  <pre><code>INSTALLED_APPS = [
      'django.contrib.sites',
      'django.contrib.admin',
      'django.contrib.auth',
      'django.contrib.contenttypes',
      'django.contrib.sessions',
      'django.contrib.messages',
      'django.contrib.staticfiles',
      'dashboard',
  ]
  </code></pre>
  
  <p>wsgi.py:</p>
  
  <pre><code>sys.path.append('/home/x_dashboard/x_dashboard/')
  
  activate_this = os.path.expanduser("/home/x_dashboard/.venv/bin/activate_this.py")
  execfile(activate_this, dict(__file__=activate_this))
  
  os.environ['PYTHON_EGG_CACHE'] = '/home/x_dashboard/x_dashboard/.python-egg'
  os.environ['DJANGO_SETTINGS_MODULE'] = 'x_dashboard.settings'
  
  import django.core.handlers.wsgi
  application = django.core.handlers.wsgi.WSGIHandler()
  </code></pre>
  
  <p>Apache config:</p>
  
  <pre><code>&lt;VirtualHost *:80&gt;
     #ServerName example.com
     #ServerAlias www.example.com
     #ServerAdmin username@example.com
  
     DocumentRoot /home/x_dashboard/x_dashboard/
  
     #ErrorLog /var/www/html/example.com/logs/error.log
     #CustomLog /var/www/html/example.com/logs/access.log combined
  
     WSGIScriptAlias / /home/x_dashboard/x_dashboard/x_dashboard/wsgi_local.py
  
     #Alias /robots.txt /var/www/html/example.com/public_html/robots.txt
     #Alias /favicon.ico /var/www/html/example.com/public_html/favicon.ico
     #Alias /images /var/www/html/example.com/public_html/images
     Alias /static /var/www/x_dashboard/static
  
     &lt;Directory /home/x_dashboard/x_dashboard/x_dashboard/&gt;
       &lt;Files wsgi.py&gt;
       Order deny,allow
       Allow from all
       Require all granted
       &lt;/Files&gt;
     &lt;/Directory&gt;
  &lt;/VirtualHost&gt;
  </code></pre>
  
  <p>The <a href="https://docs.djangoproject.com/en/1.10/ref/models/options/#app-label" rel="noreferrer">Django documentation</a> says that an app_label is required for models which do not belong to an app defined in installed_apps. However,  'django.contrib.contenttypes' <em>is</em> defined in installed_apps.</p>
  
  <p>Any help appreciated.</p>