TypeError: __str__ returned non-string while trying to add Meta to Model

[Omrigan]

I were trying to add a new Meta info to model (not instance), then got this error. Adding into modelinstance or url works fine.

Environment:

Request Method: POST
Request URL: http://127.0.0.1:8000/admin/djangoseo/mymetadatamodel/add/

Django Version: 1.9.9
Python Version: 3.5.2
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.sites',
 'goto',
 'nested_inline',
 'django_jinja',
 'filer',
 'easy_thumbnails',
 'social.apps.django_app.default',
 'import_export',
 'adminsortable2',
 'admin_export',
 'djangoseo']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']

Traceback:

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/core/handlers/base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/core/handlers/base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/contrib/admin/options.py" in wrapper
  541.                 return self.admin_site.admin_view(view)(*args, **kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/utils/decorators.py" in _wrapped_view
  149.                     response = view_func(request, *args, **kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  57.         response = view_func(request, *args, **kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/contrib/admin/sites.py" in inner
  244.             return view(request, *args, **kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/contrib/admin/options.py" in add_view
  1437.         return self.changeform_view(request, None, form_url, extra_context)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/utils/decorators.py" in _wrapper
  67.             return bound_func(*args, **kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/utils/decorators.py" in _wrapped_view
  149.                     response = view_func(request, *args, **kwargs)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/utils/decorators.py" in bound_func
  63.                 return func.__get__(self, type(self))(*args2, **kwargs2)

File "/usr/lib64/python3.5/contextlib.py" in inner
  30.                 return func(*args, **kwds)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/contrib/admin/options.py" in changeform_view
  1382.                     self.log_addition(request, new_object, change_message)

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/contrib/admin/options.py" in log_addition
  714.             object_repr=force_text(object),

File "/home/oleg/coding/goto/gotosite/env/lib/python3.5/site-packages/django/utils/encoding.py" in force_text
  76.                     s = six.text_type(s)

Exception Type: TypeError at /admin/djangoseo/mymetadatamodel/add/
Exception Value: __str__ returned non-string (type ContentType)

[mic159]

Pretty sure this is a duplicate of #8

EDIT: been waiting for @romansalin to release the fix. He said he would do it in 24 hours nearly 10 months ago!

[fannyhub]

It seems not fixed as of today...