The All-in-One WP Migration Plugin has been created to ensure a successful migration for our customers. There are a lot of things going on behind the scenes to make things easy for users. One of the things that the plugin does is to contribute to the successful migration to environments with different SSL implementations. There are rare occasions where customers find that deactivating the plugin after import then gives an error of “Too many redirects”. If you aren’t really technical, then we recommend that you leave the plugin activated to help with your SSL.
WordPress uses <?php is_ssl() ?> to check if the page is using SSL (checks if HTTPS or on Port 443).
Websites behind load balancers or reverse proxies that support HTTP_X_FORWARDED_PROTO can be fixed by adding the following code to the wp-config.php file, above the require_once call:
if (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https') $_SERVER['HTTPS'] = 'on';
The All-in-One WP Migration adds this code while active. If the plugin is deactivated, you can add it manually.