A 404 error page, also called ErrorDocument 404, is essentially a page that tells the user that the resource requested does not exist. For example, if a user follows a connection, and the target page no longer exists, a 404 error page should be displayed by the webserver. However, this isn't the only work with a 404 error address.
If properly configured, it will alert the Google-Bot if a document does exist. It is important that a 404 error page returns the correct HTTP status code 404
to ensure this happens the way it should – otherwise the 404 page is faultyWeb servers or the in use Content-Management-System (CMS) are still not set up properly.This leads to either returning the HTTP status code 200 (OK) to the error page or a 301 redirect that takes both the user and Google-Bot to another domain. You should find this a faulty 404 page or a so-called soft 404 error in either case.
(ErrorDocument 404 /404.html)
The entire process, step by step:
1. Create an error page (404.html or 404.php) on the first level of the website (root-directory)
2. Open the .htaccess file – or crate one if you do not yet have one (also in the root-directory)
3. Type in “ErrorDocument 404” followed by the relative path to the error page
4. Save and request a page that does not exist, like http://www.your-domain.com/jsdhh
5. You should now see the contents of the error page 404.html
6. Use httpstatus.io (for example) to check if the correct HTTP status code 404 is returned