Django E.408, E.409 and E.410 errors on runserver

In Django 2.2.3, activating middlewears in settings is done using the variable MIDDLEWARE not MIDDLEWERE_CLASSES, check the docs here.

So simply change the variable in your settings.py from MIDDLEWARE_CLASSES to MIDDLEWARE.

Most likely this issue occurred due to creating a project with a global django package that had was of version < 2, and then running manage.py runserver with a virtualenv that has local django >= 2

Rename variables in settings.py, or add this:

MIDDLEWARE = MIDDLEWARE_CLASSES

to settings.pybecause new Django triggers errors above based on checks like this:

if not _contains_subclass(   'django.contrib.auth.middleware.AuthenticationMiddleware',    settings.MIDDLEWARE):   errors.append(checks.Error( ...

Change setting.py as pic showsChange setting.py

# MIDDLEWARE_CLASSES = [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.auth.middleware.SessionAuthenticationMiddleware',    'django.contrib.messages.middleware.MessageMiddleware',    'django.middleware.clickjacking.XFrameOptionsMiddleware',]

Also See: From CSDN