404 To Homepage is a WordPress plugin by LittleBizzy for redirecting all 404 “Not Found” errors to the homepage.
The plugin is intended to avoid user confusion (or lost leads), and to avoid abuse causes by bots that ping your site with non-existent URLs which can negatively effect search engine indexing. Additionally, it can totally eliminate the warnings created in Google GSC (Webmasters) in regard to 404 errors.
The plugin author notes: “It should be noted, however, that this method is not recommended for all websites. For example, large blogs or magazines that rely heavily on search engine traffic (such as a newspaper) should probably not use this plugin. This is because in many cases, 404 errors should be analyzed on a regular basis and then 301 redirected to the appropriate page.”
Unlike other 404 redirect plugins, 404 To Homepage “removes” any pre-existing HTTP headers, and executes ONLY a 301 redirect header pointed at the site’s homepage.
More info and download: https://wordpress.org/plugins/404-to-homepage-littlebizzy/
There are other 404 redirect plugins reviewed at: http://www.wpbeginner.com/showcase/6-best-free-404-plugins-for-wordpress/