Usually the 503 Error ( Service Unavailable ) means that the proxy got banned on that site, probably because too many requests were made in a short period of time. The ban might be temporary or not, depends on the site. Related posts: I get the error 429 Too Many Requests HTTP code 429 (Too Many Requests) I get the http code 503 I get the 403 Error Code Tagged: 503errorService Unavailable