How to create 403 Error Page

Create a page

Create a new node of type Basic page

Add content

Use below sample code to create this page.

<div class="error-page">
<h1>Error 403 - Access denied</h1>
We are very sorry, but you do not have access to this page.
</div>

You have now successfully created Error 403 (Access denied) page.

Set this page as default Error 403 page

Navigate to: Administration >> Configuration >> System

admin/config/system/site-information

And set this page as your Error 403 page and click Save Configuration button.