Traceback (most recent call last):
  File ".../pyenv/src/django/django/core/handlers/base.py", line 174, in get_response
    response = self.process_exception_by_middleware(e, request)
  File ".../pyenv/src/django/django/core/handlers/base.py", line 172, in get_response
    response = response.render()
  File ".../pyenv/src/django/django/template/response.py", line 160, in render
    self.content = self.rendered_content
  File ".../pyenv/src/django/django/template/response.py", line 137, in rendered_content
    content = template.render(context, self._request)
  File ".../pyenv/src/django/django/template/backends/django.py", line 95, in render
    return self.template.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 198, in render
    return self._render(context)
  File ".../pyenv/src/django/django/template/base.py", line 189, in _render
    return self.nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/loader_tags.py", line 170, in render
    return compiled_parent._render(context)
  File ".../pyenv/src/django/django/template/base.py", line 189, in _render
    return self.nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/loader_tags.py", line 170, in render
    return compiled_parent._render(context)
  File ".../pyenv/src/django/django/template/base.py", line 189, in _render
    return self.nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/loader_tags.py", line 66, in render
    result = block.nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/loader_tags.py", line 66, in render
    result = block.nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/defaulttags.py", line 220, in render
    nodelist.append(node.render_annotated(context))
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/loader_tags.py", line 206, in render
    return template.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 200, in render
    return self._render(context)
  File ".../pyenv/src/django/django/template/base.py", line 189, in _render
    return self.nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/defaulttags.py", line 220, in render
    nodelist.append(node.render_annotated(context))
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/defaulttags.py", line 220, in render
    nodelist.append(node.render_annotated(context))
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/defaulttags.py", line 326, in render
    return nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/defaulttags.py", line 326, in render
    return nodelist.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 960, in render
    bit = node.render_annotated(context)
  File ".../pyenv/src/django/django/template/base.py", line 927, in render_annotated
    return self.render(context)
  File ".../pyenv/src/django/django/template/base.py", line 1017, in render
    return render_value_in_context(output, context)
  File ".../pyenv/src/django/django/template/base.py", line 994, in render_value_in_context
    value = force_text(value)
  File ".../pyenv/src/django/django/utils/encoding.py", line 78, in force_text
    s = six.text_type(s)
  File ".../pyenv/src/django/django/utils/html.py", line 382, in <lambda>
    klass.__unicode__ = lambda self: mark_safe(klass_unicode(self))
  File ".../pyenv/src/django/django/forms/forms.py", line 518, in __str__
    return self.as_widget()
  File ".../pyenv/src/django/django/forms/forms.py", line 576, in as_widget
    return force_text(widget.render(name, self.value(), attrs=attrs))
  File ".../pyenv/src/django/django/forms/widgets.py", line 411, in render
    if self.is_initial(value):
  File ".../pyenv/src/django/django/forms/widgets.py", line 385, in is_initial
    getattr(value, 'url')
  File ".../pyenv/src/django/django/db/models/fields/files.py", line 68, in _get_url
    self._require_file()
  File ".../pyenv/src/django/django/db/models/fields/files.py", line 46, in _require_file
    raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)
ValueError: The 'logo' attribute has no file associated with it.