| 400 Bad Request | This response code indicates that the server detected a syntax error in the client’s request. |
| 401 Unauthorized | The service failed because of not give proper parameters like username, password |
| 402 Payment Required | This code is not yet implemented in HTTP. |
| 403 Forbidden | The request was denied for a reason the server does not want to (or has no means to) indicate to the client. |
| 404 Not Found | The document at the specified URL does not exist. |
| 405 Method Not Allowed | This code is given with the Allow header and indicates that the method used by the client is not supported for this URL. |
| 406 Not Acceptable | The URL specified by the client exists, but not in a format preferred by the client. Along with this code, the server provides the Content-Language, Content-Encoding, and Content-type headers. |
| 407 Proxy Authentication Required | The proxy server needs to authorize the request before forwarding it. Used with the Proxy-Authenticate header. |
| 408 Request Time-out | This response code means the client did not produce a full request within some predetermined time (usually specified in the server’s configuration), and the server is disconnecting the network connection. |
| 409 Conflict | This code indicates that the request conflicts with another request or with the server’s configuration. Information about the conflict should be returned in the data portion of the reply. For example, this response code could be given when a client’s request would cause integrity problems in a database. |
| 410 Gone | This code indicates that the requested URL no longer exists and has been permanently removed from the server. |
| 411 Length Required | The server will not accept the request without a Content-length header supplied in the request. |
| 412 Precondition Failed | The condition specified by one or more If… headers in the request evaluated to false. |
| 413 Request Entity Too Large | The server will not process the request because its entity-body is too large. |
| 414 Request URL Too Long | The server will not process the request because its request URL is too large. |
| 415 Unsupported Media Type | The server will not process the request because its entity-body is in an unsupported format. |
| 416 Request Range Not Satisfiable | The requested byte range is not available and is out of bounds. |
| 417 Expectation Failed | The server is unable to meet the demands of the Expect header given by the client. |
| 418 I’m a teapot | It is used to attempt to refuse coffee with a teapot. |
| 421 Misdirected Request | This request is used to direct to a server that is not able to produce any response. Generally, it is sent by a server for not producing the authorities present in the request URL. |
| 422 Unprocessable Content (WebDAV) | It occurs when the request is not followed because of semantic errors. |
| 423 Locked (WebDAV) | It refers to the locked resources. |
| 424 Failed Dependency (WebDAV) | It occurs due to the failure of a recent request. |
| 425 Too Early | It occurs when a request is made that is not processed yet. |
| 426 Upgrade Required | It refers to when the current protocol is not considered and the system is waiting so that any other protocol is generated. It generates the upgrade header. |
| 428 Precondition Required | This request comes when the request is conditional. This is used to help with the lost update problem. |
| 429 Too Many Requests | This error comes when multiple requests are made in a certain amount of time. |
| 431 Request Header Fields Too Large | This comes when header fields are large enough to proceed. This request comes in that condition. |
| 451 Unavailable for Legal Reasons | It occurs when any request is not fulfilled because of some legal reasons, it can be due to a web page being censored. |