400 Bad Request
The server fails to process the request.
You must enter the username and password to access the requested page.
You are forbidden to access the requested page.
404 Not Found
The server cannot find the requested page.
405 Method Not Allowed
You are not allowed to use the method specified in the request.
406 Not Acceptable
The response generated by the server is not acceptable to the client.
407 Proxy Authentication Required
You must use the proxy server for authentication.
408 Request Timeout
The request is timed out.
The request cannot be processed due to a conflict.
413 Payload Too Large
The request is too large.
500 internal Server Error
The request fails because the server is abnormal.
501 Not Implemented
The request fails because the server does not support the requested function.
502 Bad Gateway
The request fails because the returned response is invalid.
503 Service Unavailable
The request fails because the system is abnormal.
504 Gateway Timeout
Gateway times out.