Go to site root folder find the file wp-config.php . You can find it using a FTP client, or your Web Hosting Admin Panel.

Open the file and find this code:

define('WP_DEBUG', false);

change it to

define('WP_DEBUG', true);

Then, save the file.

This mode will enable show any PHP error on WordPress, help you debug site.

It can be useful for developers to understand what is the problem, if there’s one.