By default, when your site visitors land on a non-existent page, they will see the following:
However, you can customize this page. For that:
Create a new page in the editor.
- Edit this page - you may include a message why this error comes up, add a block with a button which will lead to the home page etc
- Change page’s URL to 404. For that open the page settings and set the correct URL in the General tab:
4. Publish the site.