Common HTTP return codes such as 4xx, 5xx

Common HTTP return codes such as 4xx, 5xx

Client Error
=====================
Request
The server cannot understand the request information because of the incorrect syntax.
401 Unauthorized
If the request requires user authentication. The loopback should contain a Www-authenticate header field that indicates the permission to request the resource.
402 Payment Required
Reserved status code
403 Forbidden
The server accepts the request, but is denied processing.
404 Not Found
The server has found any resources that match Request-uri.
405 Menthod not allowed
Request-line The requested method is not allowed through the specified URI.
406 Not acceptable
The content attribute of the requested resource could not satisfy the criteria in the request header, so the response entity could not be generated.
407 Proxy Authentication Required
Similar to the 401 response, except that the client must authenticate on the proxy server. The proxy server must return a proxy-authenticate to be used for identity questioning. The client can return a Proxy-authorization message header for verification.
408 Reqeust Timeout
The customer service side did not submit any requests within the server waiting time for processing.
409 Conflict
The request could not be completed because there was a conflict between the current state of the requested resource and the request. This code is only allowed to be used in situations where the user is considered to be able to resolve the conflict and will resubmit the new request. The response should contain enough information for the user to discover the source of the conflict.
410 Gone
The requested resource is no longer available on the server, and there are no known forwarding addresses. Such a situation should be considered permanent.
411 Length Required
The server refused to accept the request without defining the Content-length field.
412 Precondition Failed
The server failed to satisfy one or more of these when validating the prerequisites in the header field of the request.
413 Request Entity Too Large
The server refuses to process the request because the request data exceeds the scope that the server can handle. The server may close the current connection to prevent the client from continuing the request.
414 Request-uri Too Long
Server denial of service current request because the length of the URI exceeds the resolution range of the server.
415 Unsupported Media Type
The server denies the service the current request because the request data format is not supported by the requested resource.
416 Request Range Not satisfialbe
417 Expectation Failed
The expected content specified in the request header Expect cannot be satisfied by the server, or the server is a proxy server, and it has obvious evidence that the contents of the Expect are not satisfied on the next node of the current route.
422 Unprocessable Entity
The request is well-formed, but cannot be responded to because of a semantic error. (RFC 4918 WebDAV)
423 Locked
The current resource is locked. (RFC 4918 WebDAV)
424 Failed Dependency
The current request failed, such as PROPPATCH, because of an error that occurred in a previous request. (RFC 4918 WebDAV)
425 Unordered Collection
Defined in the WebDAV advanced collections draft, but does not appear in the WebDAV sequence set protocol (RFC 3658).
426 Upgrade Required
The client should switch to tls/1.0. (RFC 2817)
449 Retry With
Extended by Microsoft, the representative request should be retried after the appropriate action has been performed.

Server Error
===================================
Internal Server Error
Server encounters an exception that prevents execution of the current request
501 Not implemented
The server does not have a corresponding execution action to complete the current request.
502 Bad Gateway
An invalid response was received from the upstream server when the server acting as a gateway or agent attempted to execute the request.
503 Service Unavailable
The server cannot process the current request because of a temporary file overload.
504 Gateway Timeout
When a server acting as a gateway or agent attempts to execute a request, it fails to receive a response from the upstream server (the server that the URI identifies, such as HTTP, FTP, LDAP), or the secondary server (such as DNS).
505 Http Version not supported
The server does not support or refuses to support the HTTP version used in the request. This implies that the server cannot or does not want to use the same version as the client. The response should contain an entity that describes why the version is not supported and which protocols the server supports.
506 Variant Also negotiates
Extended by the Transparent Content negotiation Protocol (RFC 2295), there is an internal configuration error on behalf of the server: The requested negotiation meta-resource is configured to use itself in transparent content negotiation, so it is not an appropriate focus in a negotiation process.
507 Insufficient Storage
The server cannot store the content necessary to complete the request. The situation is considered to be temporary. WebDAV (RFC 4918)
509 Bandwidth Limit exceeded
The server reached the bandwidth limit. This is not an official status code, but is still widely used.
510 Not Extended
The policies needed to get resources are not met. (RFC 2774)
Unparseable Response Headers
The source station does not return a response header, only the entity content is returned

Common HTTP return codes such as 4xx, 5xx