Коды ответов HTTP сервера
Успешные
200 OK
201 Created
202 Accepted
203 Non-Authoriative Information
204 No Content
205 Reset Content
206 Partial Content
Перенаправляющие
300 Multiple Choices
301 Moved Permanently
302 Moved Temporarily
303 See Other
304 Not Modified
305 Use Proxy (proxy redirect)
Клиентские ошибки
400 Bad Request
401 Unauthorized
402 Payment Required
403 Forbidden
404 Not Found
405 Method Not Allowed
406 Not Acceptable
407 Proxy Authentication Required
408 Request Timeout
409 Confict
410 Gone
411 Length Required
412 Precondition Failed
413 Request Entity To Large
414 Request-URI Too Long
415 Unsupported Media Type
Ошибки сервера
500 Internal Server Error
501 Not Implemented
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout
505 HTTP Version Not Supported
Дополнительная информация здесь: Hypertext Transfer Protocol -- HTTP/1.0
Взято из https://forum.sources.ru