Server response status code

One 、 Status code categories

Status code classification	explain
1xx	Response —— Temporary status code , The request has been accepted , Tell the client that it should continue the request or ignore it if it has completed
2xx	success —— Indicates that the request has been successfully received , Processing completed
3xx	Redirect —— Redirect to other places ： It allows the client to make another request to complete the whole process .
4xx	Client error —— Processing error , The responsibility lies with the client , Such as ： The client requested a nonexistent resource , The client is not authorized , No access, etc
5xx	Server-side error —— Processing error , The responsibility lies in the service side , Such as ： The server threw an exception , Routing error ,HTTP Version does not support etc

Two 、 Common response status codes

Status code	English description	explain
200	OK	Client request successful , namely Handle a successful , This is the status code we most want to see
302	Found	Indicates that the requested resource has been moved to by Location Response header given URL, The browser will automatically revisit this page
304	Not Modified	Tell the client , The resources you requested have been available since the last time , The server has not changed , You can use your local cache directly . Implicit redirection
400	Bad Request	The client request has Grammar mistakes , Not understood by the server
403	Forbidden	The server receives the request , however Denial of service , such as ： No permission to access related resources
404	Not Found	The requested resource does not exist , It's usually URL Incorrect input , Or the website resources have been deleted
428	Precondition Required	The server requires conditional requests , Tell the client to access the resource , Must carry a specific request header
429	Too Many Requests	Too many requests , You can limit the number of clients requesting a resource , coordination Retry-After( How long can I request ) Use with response headers
431	Request Header Fields Too Large	The request head is too big , The server is not willing to process requests , Because its header field is too large . The request can be resubmitted after reducing the size of the request header field .
405	Method Not Allowed	The request method is wrong , For example, we should use GET Resources in request mode , It was used POST
500	Internal Server Error	An unexpected error occurred on the server . Something went wrong with the server , Hurry to read the log
503	Service Unavailable	The server is not ready to process the request , The server has just started , Not initialized yet
511	Network Authentication Required	The client needs to be authenticated to gain network access