我正在使用与往常相同的命令在 Django 2.2 中开始一个新项目：
python3 -m venv django-env
. django-env/bin/activate
pip install django
django-admin startproject mysite
cd mysite/
python3 manage.py runserver 8080
这应该会导致一个正在运行的 Django 站点，准备好编写一些代码。不幸的是，现在我遇到了一个奇怪的错误：
LookupError: No installed app with label 'admin'.
完整追溯：
Watching for file changes with StatReloader
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib64/python3.6/threading.py", line 916, in _bootstrap_inner
self.run()
File "/usr/lib64/python3.6/threading.py", line 864, in run
self._target(*self._args, **self._kwargs)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/autoreload.py", line 54, in wrapper
fn(*args, **kwargs)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/commands/runserver.py", line 109, in inner_run
autoreload.raise_last_exception()
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/autoreload.py", line 77, in raise_last_exception
raise _exception[0](_exception[1]).with_traceback(_exception[2])
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/autoreload.py", line 54, in wrapper
fn(*args, **kwargs)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/__init__.py", line 24, in setup
apps.populate(settings.INSTALLED_APPS)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/apps/registry.py", line 114, in populate
app_config.import_models()
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/apps/config.py", line 211, in import_models
self.models_module = import_module(models_module_name)
File "/usr/lib64/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/contrib/auth/models.py", line 2, in <module>
from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/contrib/auth/base_user.py", line 47, in <module>
class AbstractBaseUser(models.Model):
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/models/base.py", line 117, in __new__
new_class.add_to_class('_meta', Options(meta, app_label))
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/models/base.py", line 321, in add_to_class
value.contribute_to_class(cls, name)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/models/options.py", line 204, in contribute_to_class
self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/__init__.py", line 28, in __getattr__
return getattr(connections[DEFAULT_DB_ALIAS], item)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/utils.py", line 201, in __getitem__
backend = load_backend(db['ENGINE'])
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/utils.py", line 110, in load_backend
return import_module('%s.base' % backend_name)
File "/usr/lib64/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/backends/sqlite3/base.py", line 66, in <module>
check_sqlite_version()
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/db/backends/sqlite3/base.py", line 63, in check_sqlite_version
raise ImproperlyConfigured('SQLite 3.8.3 or later is required (found %s).' % Database.sqlite_version)
django.core.exceptions.ImproperlyConfigured: SQLite 3.8.3 or later is required (found 3.7.17).
Traceback (most recent call last):
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/apps/registry.py", line 155, in get_app_config
return self.app_configs[app_label]
KeyError: 'admin'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "manage.py", line 21, in <module>
main()
File "manage.py", line 17, in main
execute_from_command_line(sys.argv)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
utility.execute()
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/__init__.py", line 375, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/base.py", line 323, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/commands/runserver.py", line 60, in execute
super().execute(*args, **options)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/base.py", line 364, in execute
output = self.handle(*args, **options)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/commands/runserver.py", line 95, in handle
self.run(**options)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/core/management/commands/runserver.py", line 102, in run
autoreload.run_with_reloader(self.inner_run, **options)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/autoreload.py", line 579, in run_with_reloader
start_django(reloader, main_func, *args, **kwargs)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/autoreload.py", line 564, in start_django
reloader.run(django_main_thread)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/autoreload.py", line 272, in run
get_resolver().urlconf_module
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/functional.py", line 80, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/urls/resolvers.py", line 564, in urlconf_module
return import_module(self.urlconf_name)
File "/usr/lib64/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/home/ec2-user/environment/mysite/mysite/urls.py", line 20, in <module>
path('admin/', admin.site.urls),
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/utils/functional.py", line 256, in inner
self._setup()
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/contrib/admin/sites.py", line 529, in _setup
AdminSiteClass = import_string(apps.get_app_config('admin').default_site)
File "/home/ec2-user/environment/django-env/lib64/python3.6/dist-packages/django/apps/registry.py", line 162, in get_app_config
raise LookupError(message)
LookupError: No installed app with label 'admin'.
然而，在降级 Django 版本之后pip install django==2.1.8
一切都恢复正常并按预期工作。
我查看了 Django 2.2 发行说明以及向后不兼容的更改和不推荐使用的功能列表，但没有发现任何内容。任何人都可以对正在发生的事情有所了解吗？