Django Gunicorn：メタクラスベースを呼び出すときのエラー

カスタムモデルフィールド（および付随するフォームフィールド）を含むDjangoアプリケーションがあります。組み込みの開発サーバーでプロジェクトを実行すると、正常に動作します。 gunicornとサーバーのロード、しかし、次のエラーの結果は：あなたが見ることができるようにDjango Gunicorn：メタクラスベースを呼び出すときのエラー

Traceback: 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response 
    111.       response = callback(request, *callback_args, **callback_kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/contrib/admin/sites.py" in wrapper 
    214.     return self.admin_view(view, cacheable)(*args, **kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view 
    93.      response = view_func(request, *args, **kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func 
    79.   response = view_func(request, *args, **kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner 
    197.    return view(request, *args, **kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func 
    79.   response = view_func(request, *args, **kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/contrib/admin/sites.py" in index 
    382.    context_instance=context_instance 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/shortcuts/__init__.py" in render_to_response 
    20.  return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/loader.py" in render_to_string 
    188.   return t.render(context_instance) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    123.    return self._render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in _render 
    117.   return self.nodelist.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    744.     bits.append(self.render_node(node, context)) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/debug.py" in render_node 
    73.    result = node.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/loader_tags.py" in render 
    127.   return compiled_parent._render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in _render 
    117.   return self.nodelist.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    744.     bits.append(self.render_node(node, context)) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/debug.py" in render_node 
    73.    result = node.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/loader_tags.py" in render 
    127.   return compiled_parent._render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in _render 
    117.   return self.nodelist.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    744.     bits.append(self.render_node(node, context)) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/debug.py" in render_node 
    73.    result = node.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/defaulttags.py" in render 
    311.    return self.nodelist_true.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    744.     bits.append(self.render_node(node, context)) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/debug.py" in render_node 
    73.    result = node.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/defaulttags.py" in render 
    311.    return self.nodelist_true.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    744.     bits.append(self.render_node(node, context)) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/debug.py" in render_node 
    73.    result = node.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/loader_tags.py" in render 
    64.    result = block.nodelist.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/base.py" in render 
    744.     bits.append(self.render_node(node, context)) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/debug.py" in render_node 
    73.    result = node.render(context) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/template/defaulttags.py" in render 
    437.    url = reverse(view_name, args=args, kwargs=kwargs, current_app=context.current_app) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in reverse 
    391.    *args, **kwargs))) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in reverse 
    312.   possibilities = self.reverse_dict.getlist(lookup_view) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _get_reverse_dict 
    229.    self._populate() 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _populate 
    208.      for name in pattern.reverse_dict: 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _get_reverse_dict 
    229.    self._populate() 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _populate 
    208.      for name in pattern.reverse_dict: 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _get_reverse_dict 
    229.    self._populate() 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _populate 
    197.   for pattern in reversed(self.url_patterns): 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _get_url_patterns 
    279.   patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/core/urlresolvers.py" in _get_urlconf_module 
    274.    self._urlconf_module = import_module(self.urlconf_name) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/utils/importlib.py" in import_module 
    35.  __import__(name) 
File "/home/rob/projects/shipp/shipp/tickets/urls.py" in <module> 
    3. from shipp.tickets.views import TicketListView, TicketDetailView, \ 
File "/home/rob/projects/shipp/shipp/tickets/views.py" in <module> 
    15. from shipp.tickets.forms import TicketForm, TicketAttributesForm, \ 
File "/home/rob/projects/shipp/shipp/tickets/forms.py" in <module> 
    26. class TicketTimeSpentForm(forms.ModelForm): 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/forms/models.py" in __new__ 
    205.          opts.exclude, opts.widgets, formfield_callback) 
File "/home/rob/.virtualenvs/shipp/lib/python2.7/site-packages/django/forms/models.py" in fields_for_model 
    159.    formfield = f.formfield(**kwargs) 
File "/home/rob/projects/shipp/shipp/../shipp/tickets/fields.py" in formfield 
    43.   return super(TimedeltaField, self).formfield(*args, **defaults) 

Exception Type: TemplateSyntaxError at /admin/ 
Exception Value: Caught TypeError while rendering: Error when calling the metaclass bases 
    must be type, not None

：

TemplateSyntaxError at /admin/ 
Caught TypeError while rendering: Error when calling the metaclass bases 
    must be type, not None

私は、障害のラインを示して完全なものにするため、以下の全体の誤差を、含めましたトレースバックから問題の原因となった行（fields.pyの43行目）は、通常のsuperコールです。なぜこのエラーが起こっているのか、あなたは何か考えていますか？上記の問題の原因となっている方法を削除すると、別の場所でも発生します。

出典

2011-06-20 Rob Golding