Python – FutureWarning : `TemplateForHostMiddleware` is deprecated. Please upgrade to the template loader

I’m building a mezzanine website.

I installed mezzanine

by typing pip install mezzanine, which installed django 1.9 (IIRC) and mezzanine.

Then I installed cartridge to upgrade django to version 1.10.8.

Now, when I run runserver at the command line, I get the following warning at the command line:

/path/to/env/lib/python3.5/site-packages/django/core/handlers/base.py:58:
FutureWarning: TemplateForHostMiddleware` is deprecated. Please
upgrade to the template loader.

How do I fix this warning – because the warning is not very clear (i.e. which template loader to upgrade and what does upgrading template loader mean?). )

See also this portion’s documentation explaining what’s going on:

Mezzanine implements host-specific templates using a template loader since version 4.3. Prior to that, the TemplateForHostMiddleware was used. If you are upgrading from a version lower than 4.3 and getting warnings in the terminal about TemplateForHostMiddleware, edit your settings.py to switch to the new loader-based approach:

• Remove TemplateForHostMiddleware from your MIDDLEWARE or MIDDLEWARE_CLASSES setting.
• Remove "APP_DIRS": True from your TEMPLATES setting.
• Add mezzanine.template.loaders.host_themes. Loader to the list of template loaders.

Your TEMPLATES setting should look like this (notice the “loaders” key):

TEMPLATES = [
  {
      "BACKEND": "django.template.backends.django.DjangoTemplates",
      "DIRS": [...],
      "OPTIONS": {
          "context_processors": [...],
          "builtins": [...],
          "loaders": [
              "mezzanine.template.loaders.host_themes. Loader",
              "django.template.loaders.filesystem.Loader",
              "django.template.loaders.app_directories. Loader",
          ]
      },
  },
]

It looks like this change to the documentation hasn’t been implemented yet http://mezzanine.jupo.org/docs/multi-tenancy.html .