Whyis my django project returning "django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet" error

Question

I am using django to try and create a website that allows usersubdomains. Something like john.stackoverflow.com. I'm currently trying to set up django tenant schamas and nothing seems to be working even though I'm following the documentation. I am trying to make the app 'main' a tenant app. So when a user goes to main it returns user.website.com. I keep getting this error though "django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet".

Here's my settings file:

INSTALLED_APPS = [
'tenant_schemas',
'main',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
]

TENANT_MODEL = "main.Client"

MIDDLEWARE = [
    'tenant_schemas.middleware.TenantMiddleware',
    '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',
]

SHARED_APPS = (
'tenant_schemas',  # mandatory, should always be before any django app
'main', # you must list the app where your tenant model resides in
'django.contrib.contenttypes',
# everything below here is optional
'django.contrib.auth',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.messages',
'django.contrib.admin',
)
TENANT_APPS = (
    'django.contrib.contenttypes',
    # your tenant-specific apps
    'main',
)
DATABASES = {
'default': {
    'ENGINE': 'tenant_schemas.postgresql_backend',
    # ..
}
}
DATABASE_ROUTERS = (
    'tenant_schemas.routers.TenantSyncRouter',
)

Answer 1

This error came in Django when at least one of apps you are using in your project, is not defined in INSTALLED_APPS section.

Are you sure that all the apps you are using are defined in that section?!