Common error codes: 200 - OK / no error 301 - Redirect 302 - Redirect 400 - Bad request 401 - Unauthorized. This page requires a login+password. 402 - Payment Required 403 - Forbidden. 404 - Page not found 405 - Method Not Allowed 406 - Not Acceptable 407 - Proxy Authentication Required 408 - Request Timeout 409 - Conflict 410 - Gone 411 - Length Required 412 - Precondition Failed 413 - Request Entity Too Large 414 - Request-URI Too Long 415 - Unsupported Media Type 416 - Requested Range Not Satisfiable 417 - Expectation Failed 500 - Internal Server error 501 - Not Implemented 502 - Bad Gateway 503 - Service Unavailable 504 - Gateway Timeout 505 - HTTP Version Not Supported 0 - Some network connection error. Most likely it is a time out. Don't worry about it if it happens with a few pages. 990 - Blocked by your robots.txt file. 999 - Undefined error. Something went wrong, but we don't know what.