HTTP return status code meaning

100: Continue The client should continue sending the request. The client SHOULD continue sending the remainder of the request, or ignore this response if the request has already completed.

101: Switching Protocols After sending the blank line at the end of this response, the server will switch to those protocols defined in the Upgrade header. Similar measures should only be taken when it is more beneficial to switch to a new protocol.

102: Continue Processing Status code extended by WebDAV (RFC 2518) indicating that processing is to be continued.

200: The request is successful. Processing method: Get the content of the response and process it

201: The request completed, resulting in the creation of a new resource. The URI of the newly created resource is available in the entity of the response Handling: not encountered in the crawler

202: The request is accepted, but the processing has not yet been completed. Processing method: blocking waiting

204: The server has fulfilled the request, but no new information has been returned. If the client is a user agent, it does not need to update its own document view for this. Processing method: discard

300: This status code is not directly used by HTTP/1.0 applications, but is only used as the default interpretation for 3XX type responses. There are multiple requested resources available. Processing method: If it can be processed in the program, it will be further processed. If it cannot be processed in the program, it will be discarded.
301: The requested resource will be assigned a permanent URL, so that the resource can be accessed through the URL in the future. Processing method: Redirect to assigned URL

302: The requested resource is temporarily saved at a different URL Processing method: redirect to a temporary URL

304: The requested resource is not updated Processing method: discard

400: Illegal request Processing method: discard

401: Unauthorized Processing method: discard

403: Forbidden Processing method: discard

404: Not found Processing method: discard

500: Internal Server Error The server encountered an unexpected condition that prevented it from completing the processing of the request. Generally, this problem occurs when there is an error in the source code on the server side.

501: The server does not recognize the server does not support a function required by the current request. When the server does not recognize the requested method and cannot support its request for any resource.

502: Bad Gateway An invalid response was received from an upstream server when a server working as a gateway or proxy attempted to perform a request.

503: Service Error The server is currently unable to process the request due to temporary server maintenance or overload. This condition is temporary and will return after a period of time.