Styling the error pages

Drupal provides some suggestions for typical 4xx errors, such as File not found or Access denied.

Every time an error occurs on Drupal, the system triggers a redirect to one of those routes:

• system.401: The user is trying to access an unauthorized resource
• system.403: The user is trying to access a forbidden resource
• system.404: The user is trying to access a resource that doesn’t exist

Every time the page for one of those routes is rendered, the system looks for a related page template:

• page--401.html.twig
• page--403.html.twig
• page--404.html.twig

For example, for a Page not found error, Drupal checks whether a template called page--404.html.twig exists in the currently enabled theme.

To see this in action, follow these steps:

1. Create a templates/layout/page--404.html.twig file with this content:

   {{ include('@organisms/page-error.html.twig', {

     srMessage: 'Error'|t...