title: django not saving media files in production
body: <p>I set up django project on ubuntu 18.04 and apache2 but there is a problem.
  Media files don't save.
  When I try to upload file using django-filer I get 500 internal server error(I wrote simple plugin with charfield and filefield - the same happens) independently from DEBUG=True/False setting.
  I uploaded few files using manage.py runserver and this works great - I can even use these files in production but an attempt to upload any new one cause error
  settings.py:</p>
  <pre><code>MEDIA_URL = '/media/'
  MEDIA_ROOT = '/mysite/public/media/'
  STATIC_URL = '/static/'
  STATIC_ROOT = '/mysite/public/static/'
  STATICFILES_DIRS = [os.path.join(BASE_DIR,'static')]
  </code></pre>
  <p>apache configuration:</p>
  <pre><code>alias /static /mysite/public/static
  &lt;Directory /mysite/public/static&gt;
  Require all granted
  &lt;/Directory&gt;
  
  alias /media /mysite/public/media
  &lt;Directory /mysite/public/media&gt;
  Require all granted
  &lt;/Directory&gt;
  
  &lt;Directory /mysite/src/proj&gt;
  &lt;Files wsgi.py&gt;
  Require all granted
  &lt;/Files&gt;
  &lt;/Directory&gt;
  
  WSGIDaemonProcess mysite python-home=/mysite/venv python-path=/mysite/src/
  WSGIProcessGroup mysite
  WSGIScriptAlias / /mysite/src/proj/wsgi.py
  </code></pre>
  <p>In conclusion:
  manage.py runserver works great.
  On production server I can manage files which were uploaded earlier but an attempt to upload a new one cause error 500.</p>