You should add [XYZ] to the httpd Config File

You may receive the following warning.

As you’re on Apache, you should add the following include to the website httpd config file:
Include /Path_To_WordPress/wp-content/uploads/wpseo-redirects/.redirects

The cause

When you disable PHP redirects and generate a separate redirect file, the plugin writes all redirects to a custom file. However, your server doesn’t know how to use the custom file.

The solution

The command in the warning tells the server to use the custom file. Contact your web host or server administrator for instructions on how to edit your website’s httpd.conf file.

Due to security reasons it is not possible for the plugin to check the full pathway of the server. This means even if you know you added the pathway to your httpd.conf file the message will still appear.