djangoでrunserverで開発用サーバを起動しようとしたら、「raise ImproperlyConfigured」が出て起動しない場合の確認と対応

状況

• python3 manage.py runserverなどで開発用サーバを起動しようとしたら、以下のメッセージが出て起動しませんでした。

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/django/urls/resolvers.py", line 591, in url_patterns
    iter(patterns)
TypeError: 'module' object is not iterable

(略)

    raise ImproperlyConfigured(msg.format(name=self.urlconf_name)) from e
django.core.exceptions.ImproperlyConfigured: The included URLconf '' does not appear to have any patterns in it. If you see valid patterns in the file then the issue is probably caused by a circular import.

確認ポイント

• ソースファイル名とdoes not appear to have any patterns in it.とが出ているので、該当ソースを見る

原因

• 「urlpatterns」を「urlpetterns」と打ち間違えていた

対応

• エラーメッセージに出ていた該当ファイルのタイプミスを修正

メッセージの全体

$ python3 manage.py runserver 0.0.0.0:8000
Watching for file changes with StatReloader
Performing system checks...

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/django/urls/resolvers.py", line 591, in url_patterns
    iter(patterns)
TypeError: 'module' object is not iterable

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3.6/threading.py", line 916, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.6/threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.6/dist-packages/django/utils/autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/commands/runserver.py", line 118, in inner_run
    self.check(display_num_errors=True)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/base.py", line 396, in check
    databases=databases,
  File "/usr/local/lib/python3.6/dist-packages/django/core/checks/registry.py", line 70, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "/usr/local/lib/python3.6/dist-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/usr/local/lib/python3.6/dist-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/usr/local/lib/python3.6/dist-packages/django/urls/resolvers.py", line 409, in check
    messages.extend(check_resolver(pattern))
  File "/usr/local/lib/python3.6/dist-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/usr/local/lib/python3.6/dist-packages/django/urls/resolvers.py", line 408, in check
    for pattern in self.url_patterns:
  File "/usr/local/lib/python3.6/dist-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/local/lib/python3.6/dist-packages/django/urls/resolvers.py", line 598, in url_patterns
    raise ImproperlyConfigured(msg.format(name=self.urlconf_name)) from e
django.core.exceptions.ImproperlyConfigured: The included URLconf '' does not appear to have any patterns in it. If you see valid patterns in the file then the issue is probably caused by a circular import.