django-mailbox: django-mailbox template error

Environment:

Request Method: GET
Request URL: http://hirewiz.tk/admin/django_mailbox/message/1/change/

Django Version: 1.9
Python Version: 3.6.2
Installed Applications:
['pages.apps.PagesConfig',
 'django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django_mailbox']
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.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']


Template error:
In template /usr/local/lib64/python3.6/site-packages/django/contrib/admin/templates/admin/change_form.html, error at line 32
   2   22 : </div>
   23 : {% endblock %}
   24 : {% endif %}
   25 : 
   26 : {% block content %}<div id="content-main">
   27 : {% block object-tools %}
   28 : {% if change %}{% if not is_popup %}
   29 :   <ul class="object-tools">
   30 :     {% block object-tools-items %}
   31 :     <li>
   32 :         {% url opts|admin_urlname:'history' orig inal.pk|admin_urlquo te as history_url %}
   33 :         <a href="{% add_preserved_filters history_url %}" class="historylink">{% trans "History" %}</a>
   34 :     </li>
   35 :     {% if has_absolute_url %}<li><a href="{{ absolute_url }}" class="viewsitelink">{% trans "View on site" %}</a></li>{% endif %}
   36 :     {% endblock %}
   37 :   </ul>
   38 : {% endif %}{% endif %}
   39 : {% endblock %}
   40 : <form {% if has_file_field %}enctype="multipart/form-data" {% endif %}action="{{ form_url }}" method="post" id="{{ opts.model_name }}_form" novalidate>{% csrf_token %}{% block form_top %}{% endblock %}
   41 : <div>
   42 : {% if is_popup %}<input type="hidden" name="{{ is_popup_var }}" value="1" />{% endif %}


Traceback:

File "/usr/local/lib64/python3.6/site-packages/django/db/models/options.py" in get_field
  580.             return self.fields_map[field_name]

During handling of the above exception ('envelope_headers'), another exception occurred:

File "/usr/local/lib64/python3.6/site-packages/django/contrib/admin/utils.py" in lookup_field
  273.         f = _get_non_gfk_field(opts, name)

File "/usr/local/lib64/python3.6/site-packages/django/contrib/admin/utils.py" in _get_non_gfk_field
  307.     field = opts.get_field(name)

File "/usr/local/lib64/python3.6/site-packages/django/db/models/options.py" in get_field
  582.             raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name))

During handling of the above exception (Message has no field named 'envelope_headers'), another exception occurred:

File "/usr/local/lib64/python3.6/site-packages/django/core/handlers/base.py" in get_response
  174.                     response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib64/python3.6/site-packages/django/core/handlers/base.py" in get_response
  172.                     response = response.render()

File "/usr/local/lib64/python3.6/site-packages/django/template/response.py" in render
  160.             self.content = self.rendered_content

File "/usr/local/lib64/python3.6/site-packages/django/template/response.py" in rendered_content
  137.         content = template.render(context, self._request)

File "/usr/local/lib64/python3.6/site-packages/django/template/backends/django.py" in render
  95.             return self.template.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  206.                     return self._render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in _render
  197.         return self.nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/loader_tags.py" in render
  173.         return compiled_parent._render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in _render
  197.         return self.nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/loader_tags.py" in render
  173.         return compiled_parent._render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in _render
  197.         return self.nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/loader_tags.py" in render
  69.                 result = block.nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/loader_tags.py" in render
  69.                 result = block.nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/defaulttags.py" in render
  220.                     nodelist.append(node.render_annotated(context))

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/loader_tags.py" in render
  209.                 return template.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  208.                 return self._render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in _render
  197.         return self.nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/defaulttags.py" in render
  220.                     nodelist.append(node.render_annotated(context))

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/defaulttags.py" in render
  220.                     nodelist.append(node.render_annotated(context))

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/defaulttags.py" in render
  326.                 return nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/defaulttags.py" in render
  326.                 return nodelist.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  988.                 bit = node.render_annotated(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render_annotated
  955.             return self.render(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in render
  1039.             output = self.filter_expression.resolve(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in resolve
  705.                 obj = self.var.resolve(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in resolve
  846.             value = self._resolve_lookup(context)

File "/usr/local/lib64/python3.6/site-packages/django/template/base.py" in _resolve_lookup
  909.                             current = current()

File "/usr/local/lib64/python3.6/site-packages/django/contrib/admin/helpers.py" in contents
  194.             f, attr, value = lookup_field(field, obj, model_admin)

File "/usr/local/lib64/python3.6/site-packages/django/contrib/admin/utils.py" in lookup_field
  285.             value = attr(obj)

File "/usr/local/lib/python3.6/site-packages/django_mailbox/admin.py" in envelope_headers
  75.         email = msg.get_email_object()

File "/usr/local/lib/python3.6/site-packages/django_mailbox/models.py" in get_email_object
  728.         return self._rehydrate(flat)

File "/usr/local/lib/python3.6/site-packages/django_mailbox/models.py" in _rehydrate
  624.                     self._rehydrate(part)

File "/usr/local/lib/python3.6/site-packages/django_mailbox/models.py" in _rehydrate
  653.                         attachment.document.read()

File "/usr/local/lib64/python3.6/site-packages/django/core/files/utils.py" in <lambda>
  19.     read = property(lambda self: self.file.read)

File "/usr/local/lib64/python3.6/site-packages/django/db/models/fields/files.py" in _get_file
  51.             self._file = self.storage.open(self.name, 'rb')

File "/usr/local/lib64/python3.6/site-packages/django/core/files/storage.py" in open
  37.         return self._open(name, mode)

File "/usr/local/lib64/python3.6/site-packages/django/core/files/storage.py" in _open
  201.         return File(open(self.path(name), mode))

Exception Type: FileNotFoundError at /admin/django_mailbox/message/1/change/
Exception Value: [Errno 2] No such file or directory: '/home/ec2-user/hirewiz/mailbox_attachments/2018/03/07/1c019db8888843908c5d243fd37c0df9.pdf'