Internal Server Error: /wizard/advocate

Traceback:

File "/usr/lib/python3/dist-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)
File "/usr/lib/python3/dist-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)
File "/usr/lib/python3/dist-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/lib/python3/dist-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)
File "/srv/nm.debian.org/nm2/backend/mixins.py" in dispatch
  77.         return super(VisitorMixin, self).dispatch(request, *args, **kwargs)
File "/usr/lib/python3/dist-packages/django/views/generic/base.py" in dispatch
  97.         return handler(request, *args, **kwargs)
File "/usr/lib/python3/dist-packages/django/views/generic/edit.py" in post
  142.             return self.form_valid(form)
File "/srv/nm.debian.org/nm2/wizard/views.py" in form_valid
  55.         return self.render_to_response(self.get_context_data(form=form))
File "/srv/nm.debian.org/nm2/wizard/views.py" in get_context_data
  35.                 for p in bmodels.Person.objects.filter(query).order_by("ldap_fields__uid", "ldap_fields__cn"):
File "/usr/lib/python3/dist-packages/django/db/models/manager.py" in manager_method
  82.                 return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/usr/lib/python3/dist-packages/django/db/models/query.py" in filter
  892.         return self._filter_or_exclude(False, *args, **kwargs)
File "/usr/lib/python3/dist-packages/django/db/models/query.py" in _filter_or_exclude
  910.             clone.query.add_q(Q(*args, **kwargs))
File "/usr/lib/python3/dist-packages/django/db/models/sql/query.py" in add_q
  1290.         clause, _ = self._add_q(q_object, self.used_aliases)
File "/usr/lib/python3/dist-packages/django/db/models/sql/query.py" in _add_q
  1312.                     current_negated, allow_joins, split_subq, simple_col)
File "/usr/lib/python3/dist-packages/django/db/models/sql/query.py" in _add_q
  1318.                     split_subq=split_subq, simple_col=simple_col,
File "/usr/lib/python3/dist-packages/django/db/models/sql/query.py" in build_filter
  1190.         lookups, parts, reffed_expression = self.solve_lookup_type(arg)
File "/usr/lib/python3/dist-packages/django/db/models/sql/query.py" in solve_lookup_type
  1049.         _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
File "/usr/lib/python3/dist-packages/django/db/models/sql/query.py" in names_to_path
  1420.                                      "Choices are: %s" % (name, ", ".join(available)))
Exception Type: FieldError at /wizard/advocate
Exception Value: Cannot resolve keyword 'username' into field. Choices are: am, audit_log, bio, created, date_joined, email, expires, fd_comment, fprs, fullname, groups, id, identities, inconsistencies, is_staff, is_superuser, key, last_login, last_vote, ldap_fields, legacy_processes,
logentry, pending, processes, requirement, status, status_changed, status_description, user_permissions