HTTP status code types

You can check for web service failures through the WhaTap URL monitoring. A warning alert is sent if the status code returned from the web service is 4xx or 5xx. These status codes are called HTTP Status Code. A typical example is “404 Not Found.”

The status code consists of three digits, with the first digit being 1 through 5. If the first digit is 4 or 5, this is abnormal and the site administrator must be aware of it immediately.

• 1xx (INFO): The request has been received and the process is still in progress.

• 2xx (Success): The request was successfully received, recognized, and processed.

• 3xx (Redirect): Additional actions are required to complete the request.

• 4xx (Client Error): The syntax of the request is wrong or the request cannot be processed.

• 5xx (Server Error): The server failed to process a valid request.

Note

For more information about HTTP status codes, see the following link:

• W3 RFC 2616 status code summary

• Mozilla Foundation status code summary

• IETF's RFC 2616

1XX: Information responses

If the status code begins with "1," it indicates that the server has received requests and the clients connected to the server must perform tasks. The code is not supported in HTTP 1.0.

• 100 Continue

  Response code that indicates the processing status. This indicates that it informs that you can ignore the request if there is no issue with the current progress and the clients are still requesting or they have already completed the request.

• 101 Switching Protocol

  The 101 response code is sent in response to the upgrade request header sent by a client. This code indicates that the server is to accept the client's upgrade request and change the protocol. It is mainly used when switching the WebSocket protocol.

• 102 Processing(WebDAV)

  This response code indicates that the server has received the request and is processing it but cannot provide the final response yet.

2XX: Successful responses

• 200 OK

  The request has been processed successfully. Information is returned in response to the request.

• 201 Created

  The request was processed successfully and a new resource was created as a result. This response is primarily used after a POST request or some PUT requests.

• 202 Accepted

  The request was received but has not been processed yet. This response does not specify that request processing may occur asynchronously and the results may be delivered via HTTP responses. It is used when another process is processing requests, or when the server is processing the request as a batch process.

• 203 Non-Authoritative Information

  This indicates that the returned meta data does not belong to the origin server and has been collected from local or third-party copies. In this case, a 200 OK response must come first.

• 204 No Content

  The request was processed successfully but there is no content to return. However, the header may be valid, and the user agent may update the cached headers with the latest information.

• 205 Reset Content

  This indicates that after the request has been completed, the user agent must reset the document view that sent the request.

• 206 Partial Content

  It is used when a client requests partial content via the range header. The web server sends the portion of the data specified in the Range header along with the '206 Partial Content' response code.

• 207 Multi-Status

  Multi-state responses are used in the situation that includes multiple status codes from multiple resources. It is mainly used in WebDAV (Web Distributed Authoring and Visioning).

• 208 Already Reported

  Prostat (a portmanteau of Property and Status) is a response property that is used to avoid repeatedly listing multiple internal members bound to the same collection. It is used in the Web Distributed Authoring and Visioning (WebDAV).

• 226 IM Used (HTTP Delta encoding)

  It indicates that the server has processed a GET request and the response contains the current instance to which one or more instance operations have been applied.

3XX: Redirection messages

• 300 Multiple Choice

  This indicates that more than one response is possible to a request. The user agent or user must select one of them. There is no standardized response selection method.

• 301 Moved Permanently

  This indicates that the URI of the requested resource has been permanently changed. A new URI may be provided in the response.

• 302 Found

  This indicates that the URI of the requested resource has been temporarily changed. A new URI may be provided later, and the client must use the same URI in upcoming requests.

• 303 See Other

  The server instructs the client to obtain the requested resources via the GET request from different URIs.

• 304 Not Modified

  It is used for caching purposes. It notifies the client that the response has not been modified, and the client can continue to use the cached version.

• 305 Use Proxy

  It is defined in the previous HTTP specification, and it indicates that the requested response must be connected through the proxy. Due to security concerns about in-band settings for proxies, its use is gradually decreasing.

• 306 Unused

  Currently, it is not used and reserved for future uses. It is used in the versions prior to HTTP 1.1.

• 307 Temporary Redirect

  This indicates that the resources requested by the client are on a different URI and must be requested using the same method as in the previous request. Similar to 302 Found, but 307 Temporary Redirect requires that you must not change the used HTTP method. If the first request is a POST, the second request must also be a POST.

• 308 Permanent Redirect

  This indicates that the resources are permanently at a different URI. Similar to 301 Moved Permanently, but in 308 Permanent Redirect, the used HTTP method must not be changed. If the first request is a POST, the second request must also be a POST.

4XX: Client error responses

• 400 Bad Request

  This response indicates that the request's syntax is wrong and the server cannot detect it.

• 401 Unauthorized

  Although the HTTP standard clearly specifies "unauthorized," in reality this response indicates "unauthenticated." The client must be authenticated to receive the requested response.

• 402 Payment Required

  This response code is reserved for future uses. It is intended for use in digital payment systems but is not currently in use.

• 403 Forbidden

  The client does not have permission to access the content. The server sends an appropriate response to reject the request. The difference with 401 Unauthorized is that the server recognizes the client.

• 404 Not Found

  The server could not find the requested resource. In browsers, this indicates an unknown URL. The API may indicate that the endpoint is appropriate but the resource does not exist. The server may send this response instead of 403 to hide resources from unauthenticated clients. This response code is the most widely known on the web.

• 405 Method Not Allowed

  The requested method is known to the server, but its use is prohibited. For example, deleting resources from a specific API may be prohibited. Required methods (GET and HEAD) cannot be removed and cannot return this error code.

• 406 Not Acceptable

  The server sends this response when it cannot find content that meets the specifications specified by the user agent.

• 407 Proxy Authentication Required

  This response is similar to 401 Unauthorized, but it indicates that proxy authentication is required.

• 408 Request Timeout

  The server sends this response when it attempts to terminate an idle connection. Some browsers such as Chrome, Firefox 27+, and IE 9, can use the HTTP pre-connection mechanism to receive this response. Some servers may be disconnected without sending this message.

• 409 Conflict

  This response is sent when a request conflicts with the current status of the server.

• 410 Gone

  This response is sent when the requested content has been permanently deleted from the server and is no longer available. The client must remove its cache and link to resources.

• 411 Length Required

  The server rejects the requests that do not have the Content-Length header field defined.

• 412 Precondition Failed

  This response is sent when the preconditions in the client's headers do not match those of the server.

• 413 Payload Too Large

  The requested entities exceeded the limit defined by the server. The server can close the connection or respond it with including the Retry-After header field.

• 414 URI Too Long

  The length of the URI requested by the client exceeds the limit that the server can handle.

• 415 Unsupported Media Type

  The format of the requested media is not supported by the server, so the server rejects the request.

• 416 Requested Range Not Satisfiable

  The range requested in the Range header field cannot be satisfied. The requested range might exceed the data size of the target URI.

• 417 Expectation Failed

  This response is sent when the requirements in the Expect request header fields are not met from the server.

• 418 I'm a teapot

  The server refuses to brew coffee in a teapot. It is one of the HTCPCP protocol status codes.

• 421 Misdirected Request

  A request directed to the server cannot generate a response. This is sent when the server is unable to generate a response by configuring the scheme and roles linked to the request URI.

• 422 Unprocessable Entity (WebDAV)

  There is no problem with the request but it cannot comply with the request due to a syntax error.

• 423 Locked (WebDAV)

  The requested resource is locked and cannot be accessed.

• 424 Failed Dependency (WebDAV)

  The current request failed because of the failure of the previous request.

• 426 Upgrade Required

  The server does not use the current protocol to process requests but may process requests if the client is upgraded to handle a different protocol. The server responds with including the required protocol in the Upgrade header.

• 428 Precondition Required

  In the server, the request must be conditional. This is to prevent the "lost updates" where the status of the server is changed by a third party while the client GETs resources, modifies them, and returns them to the server with PUT.

• 429 Too Many Requests

  It indicates that the user sent too many requests within the specified time period. ("rate limiting")

• 431 Request Header Fields Too Large

  The requested header field is too large for the server to process the request. It needs to shorten the request and retry.

• 451 Unavailable For Legal Reasons

  It indicates that the requested resources are illegal, such as web pages that have been censored by the government.

5XX: Server error responses

• 500 Internal Server Error

  This indicates that there is a problem with the server, but the exact problem cannot be clearly identified.

• 501 Not Implemented

  It indicates that the server does not support the functionality for the request.

• 502 Bad Gateway

  It indicates that the server received an invalid response from the gateway. This occurs when the server on the Internet receives an invalid response from another server.

• 503 Service Unavailable

  It indicates that the server is not ready to handle the request. This usually happens when the server is under maintenance or is overloaded. This response must provide a user-friendly page and if possible, it must include an estimated time for service recovery in the Retry-After header.

• 504 Gateway Timeout

  This indicates that the server acting as the gateway did not receive timely responses. It is mainly caused by network issues between servers.

• 505 HTTP Version Not Supported

  It indicates that the client requested an HTTP version that is not supported by the server. It is assumed that most web browsers support the HTTP 1.x. Using the latest version of the protocol is recommended for security and performance reasons.

• 506 Variant Also Negotiates

  It occurs when an internal configuration error occurs in the server, which leads to a circular reference by the transparent content negotiation for a request.

• 507 Insufficient Storage

  This occurs when the server does not have enough space to store requests. It mainly occurs in WebDAV.

• 508 Loop Detected (WebDAV)

  It occurs when the server detects an infinite loop while processing requests.

• 510 Not Extended

  This occurs when the server needs additional expansion to process the request.

• 511 Network Authentication Required

  This indicates that the client needs authentication to access the network.