ORM error on apache + wsgi

[Christian]

When I deployed the application on the serve, a Ubuntu 16.04.01, python3.5 in virtualenv, sqlite, apache2 + wsgi I experienced this "strange" error:
Environment:

Request Method: GET
Request URL: http://www.6245.it/command/send/3

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_extensions',
 'django.contrib.sites',
 'rest_framework',
 'engine',
 'formtools',
 'allauth',
 'allauth.account',
 'allauth.socialaccount']
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']



Traceback:

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/core/handlers/base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/core/handlers/base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request, *args, **kwargs)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/views/generic/base.py" in dispatch
  88.         return handler(request, *args, **kwargs)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/views/generic/base.py" in get
  157.         context = self.get_context_data(**kwargs)

File "/var/www/mailinglist/engine/views/command.py" in get_context_data
  52. 		su.delivery(kwargs["shipment_id"])

File "/var/www/mailinglist/engine/common/shipment.py" in delivery
  115. 			tu.parse()

File "/var/www/mailinglist/engine/common/template.py" in parse
  108. 			parser.feed(s)

File "/var/www/mailinglist/engine/common/template.py" in start
  64. 				p.save()

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/base.py" in save
  708.                        force_update=force_update, update_fields=update_fields)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/base.py" in save_base
  736.             updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/base.py" in _save_table
  801.                                       forced_update)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/base.py" in _do_update
  831.         filtered = base_qs.filter(pk=pk_val)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/query.py" in filter
  790.         return self._filter_or_exclude(False, *args, **kwargs)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/query.py" in _filter_or_exclude
  808.             clone.query.add_q(Q(*args, **kwargs))

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/sql/query.py" in add_q
  1243.         clause, _ = self._add_q(q_object, self.used_aliases)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/sql/query.py" in _add_q
  1269.                     allow_joins=allow_joins, split_subq=split_subq,

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/sql/query.py" in build_filter
  1203.             condition = self.build_lookup(lookups, col, value)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/sql/query.py" in build_lookup
  1097.                     lhs = self.try_transform(lhs, name, lookups)

File "/var/www/virtualenvs/mailinglist/lib/python3.5/site-packages/django/db/models/sql/query.py" in try_transform
  1115.                 (name, lhs.output_field.__class__.__name__))

Exception Type: FieldError at /command/send/3
Exception Value: Unsupported lookup 'exact' for AutoField or join on the field not permitted.

When I run the same application with the same data with the builtin development server the error doesn't raise. I've attached the requirements (obtained via pip freeze) and the file with the full code.

The strange think is that after one or two "F5" to reload the page the code works without errors.