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First, I will look at each status code and its corresponding word (eg:200 OK304 No Modified404 Not Found), then understand the long text explanation behind the word, summarize a short paragraph based on your understanding, and finally put all of them together to remember. When the browser reports a status code, it usually follows the corresponding word after the status code.
When the browser requests services from the web server, errors, redirects, and other issues may occur.
The following lists a series of possible HTTP status messages that may be returned:
| Message: | Description: |
|---|---|
| 100 Continue | The server has received only a partial request, but once the server has not refused the request, the client should continue to send the remaining part of the request. |
| 101 Switching Protocols | Server protocol conversion: The server will comply with the customer's request to switch to another protocol. |
| 103 Checkpoint | Suggested recovery request for recovery failure of PUT or POST requests. |
| Message: | Description: |
|---|---|
| 200 OK | Request successful (this is the standard response to a successful HTTP request). |
| 201 Created | The request has been created and a new resource has been created. |
| 202 Accepted | The request to be processed has been accepted, but the processing is not complete. |
| 203 Non-Authoritative Information | The request has been successfully processed, but some response headers may be incorrect because a copy of another document is being used. |
| 204 No Content | The request has been successfully processed, but no new document has been returned. The browser should continue to display the original document. If the user regularly refreshes the page and the Servlet can determine that the user's document is sufficiently new, this status code is very useful. |
| 205 Reset Content | The request has been successfully processed, but no new document has been returned. However, the browser should reset the content it displays. It is used to force the browser to clear form input content. |
| 206 Partial Content | The client sent a GET request with a Range header, and the server completed it. |
| Message: | Description: |
|---|---|
| 300 Multiple Choices | Multiple choices. Link list. Users can choose a link to reach the destination. Up to five addresses are allowed. |
| 301 Moved Permanently | The requested page has been redirected to a new URL. |
| 302 Found | The requested page has been temporarily redirected to a new URL. |
| 303 See Other | The requested page can be found at another URL. |
| 304 Not Modified | The document was not modified as expected. The client has a buffered document and sent a conditional request (usually providing If-Modified-The Since header indicates that the client only wants documents updated after the specified date). The server tells the client that the previously buffered document can still be used. |
| 305 Use Proxy | The document requested by the client should be retrieved through the proxy server indicated by the Location header. |
| 306 Switch Proxy | Currently not in use, but the code is still retained. |
| 307 Temporary Redirect | The requested page has been temporarily moved to a new URL. |
| 308 Resume Incomplete | Suggested recovery request for recovery failure of PUT or POST requests. |
| Message: | Description: |
|---|---|
| 400 Bad Request | The server was unable to understand the request due to a syntax error. |
| 401 Unauthorized | The request is legal, but access to the requested page is prohibited. This is because the requested page requires authentication, and the client did not provide it or the authentication failed. |
| 402 Payment Required | This code is not yet available for use. |
| 403 Forbidden | The request is legal, but access to the requested page is prohibited. |
| 404 Not Found | The server cannot find the requested page. |
| 405 Method Not Allowed | The method specified in the request is not allowed. |
| 406 Not Acceptable | The response generated by the server cannot be accepted by the client. |
| 407 Proxy Authentication Required | The user must first authenticate using a proxy server, so that the request will be processed. |
| 408 Request Timeout | The request exceeded the server's waiting time. |
| 409 Conflict | The request cannot be completed due to a conflict. |
| 410 Gone | The requested page is not available. |
| 411 Length Required | "Content"-The "Content-Length" was not defined. If there is no such content, the server will not accept the request. |
| 412 Precondition Failed | The preconditions in the request were evaluated by the server as failed. |
| 413 Request Entity Too Large | The server will not accept the request because the requested entity is too large. |
| 414 Request-URI Too Long | The server will not accept the request due to the URL being too long. This occurs when a POST request is converted into a GET request with a long query string. |
| 415 Unsupported Media Type | The server will not accept the request due to the unsupported media type. |
| 416 Requested Range Not Satisfiable | The client requested a partial document, but the server cannot provide the requested part. |
| 417 Expectation Failed | The server cannot fulfill the request header specified by the client in the request. |
| Message: | Description: |
|---|---|
| 500 Internal Server Error | The request was not completed. The server encountered an unforeseen situation. |
| 501 Not Implemented | The request was not completed. The server does not support the requested function, or the server cannot complete the request. |
| 502 Bad Gateway | The request was not completed. When the server acts as a gateway or proxy, it received an invalid response from the upstream server. |
| 503 Service Unavailable | The server is currently unavailable (overloaded or down). |
| 504 Gateway Timeout | Gateway Timeout. When the server acts as a gateway or proxy, it did not receive a timely response from the upstream server. |
| 505 HTTP Version Not Supported | The server does not support the HTTP protocol version specified in the request. |
| 511 Network Authentication Required | Users need to provide authentication to obtain network access. |