508 error means that your cPanel account's resource usage has reached a limit, and our server is actively blocking requests to your websites to reduce your cPanel's resource usage.
508 error is common when you have many domains, one or more of your websites are broken, or your website or websites are being attacked.
You can see your cPanel account's resource usage in cPanel, right in the sidebar. Also, visit "CPU and Concurrent Connection Usage" in cPanel to view more info about your account resource usage.