Twig: How to show static text in the template to the Anonymous User?

Question

On a Drupal 8.9.13 website, I've removed the permission "View published content" from the Anonymous user. By default, when someone visits the front page, Drupal will then display:

Access denied

You are not authorized to access this page.

I want to replace this with some other text, e.g.

Please create an account to see our content.

To do this I try to create something like this in page--front.html.twig.

{% if not logged_in %}
<p>Please create an account to see our content.</p>
{% endif %}

However, I am stuck 😞.

1. I am not able to get rid of the "Access denied" text for the anonymous user.
2. I can't get the the text "Please create an account to see our content." to show for the Anonymous user. (If I remove "not" from the if-test it shows up as expected on the front page for the Authenticated user).

The site's theme is an otherwise unmodified subtheme of Bootstrap Barrio 5.1.4, but I don't think the problem is theme-dependent. Rather, the problem is that I don't understand the interplay between Twig and permissions (IMHO, there should be none).

Answer 1

Add a page--403.html.twig template to your theme.

See this change record: https://www.drupal.org/node/2960810

If you only want to change the default message you don't need a template. You can configure a node as access denied message in /admin/config/system/site-information.

Caveat for the non-template solution (as commented by @FreeRadical): If you restrict access to all nodes you have to find a different type of content. Could be a small module providing a custom controller which returns the static text.

BTW the themed page--403.html.twig is built in a subrequest which only job is to return a themed page with blocks. It's too late to make decisions on what to do with a 403 exception at this point. If you want to replace the core handling of a 403 exception (returning a themed subrequest) use an exception subscriber with default priority. See https://drupal.stackexchange.com/a/245211/47547