YouTipHTTP Status Codes | Novice Tutorial
When a visitor accesses a web page, the visitor's browser sends a request to the server where the web page is located. Before the browser receives and displays the web page, the server where the web page is located will return an information header (server header) containing an HTTP status code to respond to the browser's request.
The English term for HTTP status codes is HTTP Status Code.
Below are common HTTP status codes:
- 1xx (Informational Status Codes): Indicates that the received request is being processed.
- 2xx (Success Status Codes): Indicates that the request was processed normally.
- 3xx (Redirection Status Codes): Requires subsequent operations to complete this request.
- 4xx (Client Error Status Codes): Indicates that the request contains syntax errors or cannot be completed.
- 5xx (Server Error Status Codes): The server encountered an error during the process of handling the request.
HTTP Status Code Classification
HTTP status codes consist of three decimal digits, with the first decimal digit defining the type of status code. Responses are divided into five categories: informational responses (100β199), successful responses (200β299), redirections (300β399), client errors (400β499), and server errors (500β599):
| Classification | Classification Description |
|---|---|
| 1** | Information, server received request, requires requester to continue executing operation |
| 2** | Success, operation successfully received and processed |
| 3** | Redirection, further operations needed to complete request |
| 4** | Client error, request contains syntax errors or cannot complete request |
| 5** | Server error, server encountered error during processing of request |
HTTP status code list:
| Status Code | Status Code English Name | Chinese Description |
|---|---|---|
| 100 | Continue | Continue. Client should continue its request |
| 101 | Switching Protocols | Switch protocols. Server switches protocols according to client's request. Can only switch to higher-level protocols, for example, switching to new version of HTTP protocol |
| 200 | OK | Request successful. Generally used for GET and POST requests |
| 201 | Created | Created. Successfully requested and created new resource |
| 202 | Accepted | Accepted. Request has been accepted but not yet fully processed |
| 203 | Non-Authoritative Information | Non-authoritative information. Request successful. But returned meta information is not from original server, but from a copy |
| 204 | No Content | No content. Server successfully processed but returned no content. When webpage is not updated, can ensure browser continues displaying current document |
| 205 | Reset Content | Reset content. Server processed successfully, user terminal (for example: browser) should reset document view. Can clear browser form fields through this return code |
| 206 | Partial Content | Partial content. Server successfully processed partial GET request |
| 300 | Multiple Choices | Multiple choices. Requested resource may include multiple locations, response may return a list of resource characteristics and addresses for user terminal (for example: browser) selection |
| 301 | Moved Permanently | Permanently moved. Requested resource has been permanently moved to new URI, returned information will include new URI, browser will automatically redirect to new URI. Any future new requests should use new URI instead |
| 302 | Found | Temporarily moved. Similar to 301. But resource is only temporarily moved. Client should continue using original URI |
| 303 | See Other | See other address. Similar to 301. Use GET and POST requests to view |
| 304 | Not Modified | Not modified. Requested resource not modified, when server returns this status code, no resource is returned. Client typically caches accessed resources, by providing header information indicating that client only wants resources modified after specified date |
| 305 | Use Proxy | Use proxy. Requested resource must be accessed through proxy |
| 306 | Unused | Deprecated HTTP status code |
| 307 | Temporary Redirect | Temporary redirect. Similar to 302. Use GET request for redirection |
| 400 | Bad Request | Client request has syntax error, server cannot understand |
| 401 | Unauthorized | Request requires user authentication |
| 402 | Payment Required | Reserved for future use |
| 403 | Forbidden | Server understands client request but refuses to execute this request |
| 404 | Not Found | Server cannot find resource (webpage) according to client request. Through this code, website designers can set up "resource you requested cannot be found" custom pages |
| 405 | Method Not Allowed | Method in client request is forbidden |
| 406 | Not Acceptable | Server cannot complete request according to content characteristics requested by client |
| 407 | Proxy Authentication Required | Request requires proxy authentication, similar to 401, but requester should use proxy for authorization |
| 408 | Request Time-out | Server waited too long for client to send request, timeout |
| 409 | Conflict | Server may return this code when completing client's PUT request, server encountered conflict while processing request |
| 410 | Gone | Resource requested by client no longer exists. 410 differs from 404, if resource existed before but now permanently deleted, 410 code can be used, website designers can specify new location of resource through 301 code |
| 411 | Length Required | Server cannot process client request without Content-Length |
| 412 | Precondition Failed | Client request information precondition error |
| 413 | Request Entity Too Large | Due to request entity being too large, server cannot process, therefore rejects request. To prevent continuous client requests, server may close connection. If server is temporarily unable to process, response may include Retry-After information |
| 414 | Request-URI Too Large | Requested URI too long (URI usually URL), server cannot process |
| 415 | Unsupported Media Type | Server cannot process media format attached to request |
| 416 | Requested range not satisfiable | Range requested by client is invalid |
| 417 | Expectation FailedοΌexpected failureοΌ | Server cannot satisfy expected behavior specified in Expect field of request header. |
| 418 | I'm a teapot | Status code 418 is actually an April Fools' joke. It is defined in RFC 2324, which is a joke document about Hyper Text Coffee Pot Control Protocol (HTCPCP). In this joke, status code 418 was added to HTTP protocol as a joke. |
| 500 | Internal Server Error | Server internal error, cannot complete request |
| 501 | Not Implemented | Server does not support requested function, cannot complete request |
| 502 | Bad Gateway | Gateway or proxy server attempting to execute request received invalid response from remote server |
| 503 | Service Unavailable | Due to overload or system maintenance, server temporarily unable to process client request. Delay length may be included in server's Retry-After header information |
| 504 | Gateway Time-out | Gateway or proxy server did not receive request from remote server in time |
| 505 | HTTP Version not supported | Server does not support version of HTTP protocol in request, cannot complete processing |