The All-in-One WP Migration Plugin helps our customers’ migrations go smoothly. We are doing a lot behind the scenes to help our users. One of the plugin’s functions is to aid in the successful migration to environments with different SSL implementations. On rare occasions, customers discover that deactivating the plugin after import results in an error message stating “Too many redirects.” If you aren’t particularly technical, we recommend that you leave the plugin enabled to assist with your SSL.
Technical explanation:
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';
While active, the All-in-One WP Migration plugin adds this code. If the plugin deactivates, you can re-enable it.