Werkzeug Internal Server Error

traceback.txt

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/django/contrib/staticfiles/handlers.py", line 63, in __call__
    return self.application(environ, start_response)
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/wsgi.py", line 177, in __call__
    response = self.get_response(request)
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 230, in get_response
    response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 289, in handle_uncaught_exception
    return debug.technical_500_response(request, *exc_info)
  File "/usr/local/lib/python3.5/dist-packages/django_extensions/management/technical_response.py", line 6, in null_technical_500_response
    six.reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.5/dist-packages/six.py", line 686, in reraise
    raise value
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 174, in get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 172, in get_response
    response = response.render()
  File "/usr/local/lib/python3.5/dist-packages/django/template/response.py", line 160, in render
    self.content = self.rendered_content
  File "/usr/local/lib/python3.5/dist-packages/django/template/response.py", line 137, in rendered_content
    content = template.render(context, self._request)
  File "/usr/local/lib/python3.5/dist-packages/django/template/backends/django.py", line 95, in render
    return self.template.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 206, in render
    return self._render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/test/utils.py", line 92, in instrumented_test_render
    return self.nodelist.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 992, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 959, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/loader_tags.py", line 173, in render
    return compiled_parent._render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/test/utils.py", line 92, in instrumented_test_render
    return self.nodelist.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 992, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 959, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/loader_tags.py", line 69, in render
    result = block.nodelist.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 992, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 959, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 1043, in render
    output = self.filter_expression.resolve(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 709, in resolve
    obj = self.var.resolve(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 850, in resolve
    value = self._resolve_lookup(context)
  File "/usr/local/lib/python3.5/dist-packages/django/template/base.py", line 913, in _resolve_lookup
    current = current()
  File "/usr/local/lib/python3.5/dist-packages/django/forms/forms.py", line 281, in as_p
    errors_on_separate_row=True)
  File "/usr/local/lib/python3.5/dist-packages/django/forms/forms.py", line 218, in _html_output
    'field': six.text_type(bf),
  File "/usr/local/lib/python3.5/dist-packages/django/utils/html.py", line 390, in <lambda>
    klass.__str__ = lambda self: mark_safe(klass_str(self))
  File "/usr/local/lib/python3.5/dist-packages/django/forms/boundfield.py", line 43, in __str__
    return self.as_widget()
  File "/usr/local/lib/python3.5/dist-packages/django/forms/boundfield.py", line 101, in as_widget
    return force_text(widget.render(name, self.value(), attrs=attrs))
  File "/usr/local/lib/python3.5/dist-packages/versatileimagefield/widgets.py", line 120, in render
    value
  File "/usr/local/lib/python3.5/dist-packages/versatileimagefield/widgets.py", line 88, in image_preview
    'hidden_field_id': self.get_hidden_field_id(name),
  File "/usr/local/lib/python3.5/dist-packages/versatileimagefield/widgets.py", line 58, in get_hidden_field_id
    i = name.rindex('_')
ValueError: substring not found