The default WordPress behavior for the 404 error (page not found) is to show 404 template that most of the time is a part of the active theme. With AAM 4.4 or higher you can redefine this behavior and redirect user to specific page, URL or trigger a custom PHP callback function.
There are few reasons why would you want to define 404 redirect. Primarily, you want to provide better user experience and URL, that no longer available on your website, may be redirected to page that contain more useful information than just big 404 error message.
These are couple very simple steps that will allow you to redefine 404 error handling.
= Step 1. Switch to Default Access Settings =
AAM allows you to manage access settings for any role, user or visitor separately. It is less likely that you would want to define separate 404 redirects based on who is browsing your website. That is why we made a decision to enable this feature only for default access level that is inherited by all users on your website.
= Step 2. Define your redirect rule =
With 404 Redirect feature you can define your custom redirect rule and permanently redirect users to any existing page, URL or trigger custom PHP callback function.