The four latest error status codes returned by HTTP and their meanings

If an error occurs during HTTP request, the relevant error code will be returned. A series of error codes such as 404, 429, etc., but many people don’t know what they mean. The blogger has collected and sorted it out for everyone today, and the details are in the text below. With the meaning, the problem can be solved quickly.

1. 4 uncommon error codes

428, 429, 431, 511

2. Meaning of 428 error code

428 Precondition Required, preconditions are some preset conditions that must be met when the client sends an HTTP request. A good example is the If-None-Match header, often used in GET requests. If If-None-Match is specified, the client will only re-receive the response if the ETag in the response changes. Another example of a prerequisite is the If-Match header, typically used on PUT requests to indicate resources that have only been updated but not changed. This is used when multiple clients are using the HTTP service to prevent each other from overwriting the same content. When the server uses the 428 Precondition Required status code, it means that the client must send the above request header to perform the request operation. This method provides an efficient way for the server to prevent "lost update" problems from occurring.

3. Meaning of 429 error code

429 Too Many Requests (too many requests), this status code is very useful when you need to limit the number of client requests for a certain service, that is, limit the request speed. Before this, there were some similar status codes. For example "509 Bandwidth Limit Exceeded". If you want to limit the number of client requests to the service, you can use the 429 status code and include a Retry-After response header to tell the client how long it takes to request the service again.

4. Meaning of 431 error code

431 Request Header Fields Too Large (request header field is too large), in some cases, the HTTP request header sent by the client will become very large, then the server can send 431 Request Header Fields Too Large to indicate the problem.

5. The meaning of 511 error code

511 Network Authentication Required (requires network authentication), network authorization is required, and the client needs to authorize access to the fire network. Generally used for network access control in proxy interactions.

The above are HTTP status codes that are uncommon but often appear. Hope it helps everyone

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