YouTube error 503 is a server-side response code that means the site’s server is not available for now. It always occurs with the reminder of 503 Server Error: Service Unavailable. It can happen in any browser in any operating system, even on your smart phone, or on some applications.
YouTube error 400 happens in many situations, when we browse YouTube website on computer, when we use YouTube app on mobiles, and when we open YouTube app on smart TV. So When You Face Such type of Issues Contact YouTube Technical support Number for instant Help