Внезапное исключение в Boto3 - botocore.exceptions.EndpointConnectionError после, казалось бы, без изменений

Question

Я использую boto3 для публикации хитов на Amazon Mechnical Turk. Этот код работал в течение последних нескольких недель. Теперь он работал, и ему удалось опубликовать около 400/500 этих хитов. Это означает, что эта ошибка не возникала первые 400/500 раз, как и в предыдущие недели. Однако теперь тот же код возвращает ошибку, сообщающую, что конечная точка URL неверна. Конечная точка не изменилась. Что происходит?

Traceback (most recent call last):
      File "./manage.py", line 13, in <module>
        execute_from_command_line(sys.argv)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
        utility.execute()
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
        self.execute(*args, **options.__dict__)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
        output = self.handle(*args, **options)
      File "/home/rootadmin/opensurfaces/server/paintings/management/commands/run_bounding_box_tasks.py", line 38, in handle
        cmd.handle()
      File "/home/rootadmin/opensurfaces/server/mturk/management/commands/mtconsume.py", line 27, in handle
        consume_pending_objects_task(show_progress=True)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/celery/local.py", line 188, in __call__
        return self._get_current_object()(*a, **kw)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/celery/app/task.py", line 428, in __call__
        return self.run(*args, **kwargs)
      File "/home/rootadmin/opensurfaces/server/mturk/tasks.py", line 572, in consume_pending_objects_task
        max_assignments=max_assignments)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/django/db/models/manager.py", line 92, in manager_method
        return getattr(self.get_queryset(), name)(*args, **kwargs)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 372, in create
        obj.save(force_insert=True, using=self.db)
      File "/home/rootadmin/opensurfaces/server/mturk/models.py", line 1003, in save
        u'num_contents': self.contents.count(),
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/client.py", line 357, in _api_call
        return self._make_api_call(operation_name, kwargs)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/client.py", line 648, in _make_api_call
        operation_model, request_dict, request_context)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/client.py", line 667, in _make_request
        return self._endpoint.make_request(operation_model, request_dict)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/endpoint.py", line 102, in make_request
        return self._send_request(request_dict, operation_model)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/endpoint.py", line 137, in _send_request
        success_response, exception):
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/endpoint.py", line 231, in _needs_retry
        caught_exception=caught_exception, request_dict=request_dict)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/hooks.py", line 356, in emit
        return self._emitter.emit(aliased_event_name, **kwargs)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/hooks.py", line 228, in emit
        return self._emit(event_name, kwargs)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/hooks.py", line 211, in _emit
        response = handler(**kwargs)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/retryhandler.py", line 183, in __call__
        if self._checker(attempts, response, caught_exception):
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/retryhandler.py", line 251, in __call__
        caught_exception)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/retryhandler.py", line 277, in _should_retry
        return self._checker(attempt_number, response, caught_exception)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/retryhandler.py", line 317, in __call__
        caught_exception)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/retryhandler.py", line 223, in __call__
        attempt_number, caught_exception)
      File "/home/rootadmin/opensurfaces/venv/local/lib/python2.7/site-packages/botocore/retryhandler.py", line 359, in _check_caught_exception
        raise caught_exception
    botocore.exceptions.EndpointConnectionError: Could not connect to the endpoint URL: "https://mturk-requester.us-east-1.amazonaws.com/"

Мой awscli настроен для перехода на us-east-1. Все предыдущие вызовы этой конечной точки работают правильно.