WolfCMS comes with Page not found built in plugin which lets you create custom 404 Page not found.

Create your custom 404 page following these steps:

1. Go to the “Pages” tab and create a child page of “Home Page” (big green ”+” icon on the right).
2. Name your new page “404 page not found” and fill body area with some text like “Sorry, page does not exist” or something similar. You could also add a link to your sitemap, or generate your main menu and sub menus for the whoe site to give user some pointers. It's up to you.
3. Set the page setting to match these values:
   • Layout: -inherit-
   • Page Type: Page not found
   • Status: Hidden (Must be set to “Hidden” for plugin to function properly!)
4. Click the “Save and Close” button and you're done.