Explore the causes of HTTP status code changes

HTTP status code refers to the three-digit code used in the HTTP protocol to indicate the server response status. Each status code represents a different server response result, thereby informing the client of the execution status of the request. Different status codes reflect different reasons and error types. This article will explore the reasons why HTTP status codes are different.

First, let’s take a look at the classification of HTTP status codes. According to the first digit of the status code, HTTP status codes can be divided into 5 categories, namely:
1xx - informational status code, indicating that the request is being processed;
2xx - successful status code, indicating that the request is being processed Successfully received, understood and processed;
3xx - Redirect status code, indicating that further action is required to complete the request;
4xx - Client error status code, indicating that the client's request has an error;
5xx - Server Error status code indicates that an error occurred while the server was processing the request.

Next, we will explore the reasons why HTTP status codes are different.

1. 1xx Informational status codes
   1xx series of status codes are mainly used to deliver some temporary information or notifications to the client, such as:
2. 100 Continue (continue) : The server has received part of the request and the client can continue to send the remaining part of the request.
3. 101 Switching Protocols: The client requested switching protocols, and the server has confirmed it and is ready to switch.
4. 2xx Success status code
   2xx series status codes indicate that the server successfully received, understood and processed the client's request, for example:
5. 200 OK (success): indicates that the request was successfully processed .
6. 201 Created: Indicates that the request has been successfully processed and a new resource has been created on the server.
7. 204 No Content: Indicates that the request was successfully processed, but the server did not return any content.
8. 3xx Redirect status code
   The status code of the 3xx series indicates that further operations from the client are required to complete the request, for example:
9. 301 Moved Permanently: the requested resource Has been permanently moved to a new location.
10. 302 Found (Temporary Redirect): The requested resource has been temporarily moved to a new location.
11. 304 Not Modified: Indicates that the client's cached copy is still valid and the cached version can be used.
12. 4xx Client error status code
    The status code of the 4xx series indicates that the client's request has an error, for example:
13. 400 Bad Request: The request has a syntax error or cannot be processed understood by the server.
14. 403 Forbidden: The server refuses to execute the request due to insufficient permissions.
15. 404 Not Found: The server cannot find the requested resource.
16. 5xx Server error status code
    The status code of the 5xx series indicates that an internal error occurred when the server processed the request, for example:
17. 500 Internal Server Error: The server is executing An error was encountered while requesting.
18. 502 Bad Gateway: The server, acting as a gateway or proxy, received an invalid response from the upstream server.
19. 503 Service Unavailable: The server is temporarily unable to handle requests, usually due to overload or maintenance.

To summarize, the reasons for different HTTP status codes include temporary information transfer, successful request processing, redirect operations, client errors, and internal server errors. By understanding different status codes and their causes, you can better diagnose and solve problems in HTTP communication, improving system stability and user experience.

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