This plugin will look at another site you specify whenever a 404 error occurs and check if the requested path is there. If the path is found, it will redirect there rather than show the WP 404 page.
This is particularly useful to silently redirect over to an archival copy of a website when a major redesign has been done.
More information about this plugin can be found
on its homepage.
Once the plugin is installed and activated follow the on-screen prompt to set the URL of the site to check against. The prompt takes you to the Settings > 404 Site Checker screen in the Dashboard, which has a field for you to enter the URL of the site to check against.
If you are using this on a WordPress Multisite Network install where all sites should share one check site, you may prefer setting the check site in your
wp-config.php file using the following code:
define('TG_404_CHECK_SITE', 'https://example.com');
The plugin will always use what is defined in
wp-config.php if it is found. So if you have a check site set both ways, the one set from the 404 Site Checker screen will be ignored.