IntegrityError NOT NULL constraint failed: eventhub_event.event_id

Raised by:

django/db/backends/sqlite3/base.py (line 328)

Traceback (most recent call last):
  File "python3.5/site-packages/django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "python3.5/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "python3.5/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "python3.5/site-packages/django/contrib/auth/decorators.py", line 23, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "private.py", line 1, in private_function
    private_function()
  File "python3.5/site-packages/django/forms/models.py", line 468, in save
    self.instance.save()
  File "python3.5/site-packages/django/db/models/base.py", line 808, in save
    force_update=force_update, update_fields=update_fields)
  File "python3.5/site-packages/django/db/models/base.py", line 838, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "python3.5/site-packages/django/db/models/base.py", line 924, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "python3.5/site-packages/django/db/models/base.py", line 963, in _do_insert
    using=using, raw=raw)
  File "python3.5/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "python3.5/site-packages/django/db/models/query.py", line 1076, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "python3.5/site-packages/django/db/models/sql/compiler.py", line 1112, in execute_sql
    cursor.execute(sql, params)
  File "python3.5/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "python3.5/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "python3.5/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "python3.5/site-packages/django/db/backends/sqlite3/base.py", line 328, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: NOT NULL constraint failed: eventhub_event.event_id