Django / Python：ModuleNotFoundError：没有名为“d”的模块

Question

The project seemed fine till yesterday, but suddenly, when I tried to start the server after some settings changes today, this error pops up everytime:

Traceback (most recent call last):
  File "/PROJECT/manage.py", line 21, in <module>
    main()
  File "/PROJECT/manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.9/site-packages/django/core/management/__init__.py", line 395, in execute
    django.setup()
  File "/usr/local/lib/python3.9/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python3.9/site-packages/django/apps/registry.py", line 91, in populate
    app_config = AppConfig.create(entry)
  File "/usr/local/lib/python3.9/site-packages/django/apps/config.py", line 224, in create
    import_module(entry)
  File "/usr/local/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'd'

the project manage.py file:

#!/usr/bin/env python
"""Django's command-line utility for administrative tasks."""
import os
import sys


def main():
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'PROJECT.settings.production')
    try:
        from django.core.management import execute_from_command_line
    except ImportError as exc:
        raise ImportError(
            "Couldn't import Django. Are you sure it's installed and "
            "available on your PYTHONPATH environment variable? Did you "
            "forget to activate a virtual environment?"
        ) from exc
    execute_from_command_line(sys.argv)


if __name__ == '__main__':
    main()

Please help me solve this and please do ask if you need more information.

Thank you in advance.

EDIT: Add settings

settings/base.py

"""Django settings for PROJECT project."""

import os
from pathlib import Path

# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent.parent

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = ['*']

INTERNAL_IPS = [
    '127.0.0.1',
]


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'rest_framework',
    'rest_framework.authtoken',
    'django_filters',
    'hrm',
    'inventory',
    'notification',
    'production',
    'django_celery_beat',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'debug_toolbar.middleware.DebugToolbarMiddleware',
]

ROOT_URLCONF = 'MIST_ERP.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [BASE_DIR / 'templates'],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'MIST_ERP.wsgi.application'


# Database
# https://docs.djangoproject.com/en/3.0/ref/settings/#databases
# IN RESPECTIVE SETTINGS FILES


# Password validation
# https://docs.djangoproject.com/en/3.0/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.0/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.0/howto/static-files/

STATIC_URL = '/static/'
STATICFILES_DIRS = [
    BASE_DIR / "static",
]
# STATIC_ROOT = os.path.join(BASE_DIR, "static")


# Media Settings ( Profile photos, Project photos )

MEDIA_URL = '/media/'
MEDIA_ROOT = BASE_DIR / "media"


# AUTHENTICATION BACKENDS
AUTHENTICATION_BACKENDS = [
    "django.contrib.auth.backends.ModelBackend",
    "rest_framework.authentication.SessionAuthentication",
    "rest_framework.authentication.TokenAuthentication",
]


# REST FRAMEWORK CONFIG
REST_FRAMEWORK = {
    'DEFAULT_FILTER_BACKENDS': ['django_filters.rest_framework.DjangoFilterBackend'],
    'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.PageNumberPagination',
    'PAGE_SIZE': 10,
    'PAGINATE_BY': 10,
}

# MEMCACHED
"""
Memcached is an entirely memory-based cache server,
The fastest, most efficient type of cache supported natively by Django,
"""
CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION': '127.0.0.1:11211',
        'TIMEOUT': None,
        'OPTIONS': {
            'server_max_value_length': 1024 * 1024 * 2,
        }
    }
}


# LOGGING

LOG_PATH = BASE_DIR / 'logs'

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'handlers': {
        'file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': f'{LOG_PATH}/debug.log',
        },
        'file_ldap': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': f'{LOG_PATH}/debug_ldap.log',
        },
    },
    'loggers': {
        'django': {
            'handlers': ['file'],
            'level': 'DEBUG',
            'propagate': True,
        },
        "django_auth_ldap": {
            "level": "DEBUG",
            "handlers": ["file_ldap"],
            'propagate': True,
        }
    },
}


# SETTINGS VARS
LOGIN_URL = '/login/'

# DJANGO AUTO FIELD
DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'

development.py ( currently being used )

from PROJECT.settings.base import *
import os

DEBUG = True

INSTALLED_APPS += 'debug_toolbar'

# Database

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}

Answer 1

In the deployment.py , you should wrap the 'debug_toolbar' string in a collection, for example a list, otherwise you will add one item per character to the INSTALLED_SETTINGS , and thus then you would load as apps 'd' , 'e' , 'b' , etc.

You thus can rewrite this to:

# deployment.py

# …

INSTALLED_APPS += 

# …