[Django]-Django-signal receiver doesn't work although connected in the ready() method

As explained in the FineManual, you need to either explicitely register the appconfig in INSTALLED_APPS ie:

INSTALLED_APPS = [
    ...,
    'products.apps.ProductConfig',
    ...,
]

or declare it as default_app_config in products/__init__.py:

# products/__init__.py
default_app_config = "products.apps.ProductConfig"