When the browser requests the service from the web server, an error may occur and the server may return an error code like 404 Not Found .
These errors are commonly referred to as HTML error messages. But these messages are also called HTTP status messages. In fact, the server always returns a message for every request. The most common message is 200 OK.
Here is a list of HTTP status messages that may be returned:
1xx: Information
Notify
Describe
100 Continue
The server has received the request header and the client will proceed to send the request body
101 Switching Protocols
The requesting party requested the server to transfer the protocol
103 Early Hints
Used with the Link header to allow the browser to start preloading the resource while the server is preparing a response
2xx: Success
Notify
Describe
200 OK
Request approved (this is the standard response for successful HTTP requests)
201 Created
The request was made and a new resource was created
202 Accepted
The request has been accepted for processing, but the processing is not complete yet
203 Non-Authoritative Information
The request was processed successfully but is returning information possibly from another source
204 No Content
The request was processed successfully but no content was returned
205 Reset Content
The request was processed successfully, but did not return any content and requires the requesting party to reset the document view
206 Partial Content
The server only distributes a portion of the resource by the scope header sent by the client
3xx: Redirects
Notify
Describe
300 Multiple Choices
A linked list. The user can select a link and go to that location. Up to 5 addresses
301 Moved Permanently
The requested page has moved to a new URL
302 Found
The requested page has temporarily moved to a new URL
303 See Other
The requested page can be found under a different URL
304 Not Modified
Indicates the requested page has not been modified since the last request
307 Temporary Redirect
The requested page has temporarily moved to a new URL
308 Permanent Redirect
The requested page has permanently moved to a new URL
4xx: Client error
Notify
Describe
400 Bad Request
The request could not be fulfilled due to incorrect syntax
401 Unauthorized
The request is valid, but the server refuses to respond to it. Use when authentication is possible but fails or has not been specified
402 Payment Required
Use for the future
403 Forbidden
The request is valid, but the server refuses to respond to it
404 Not Found
The requested page could not be found, but it may be available again in the future
405 Method Not Allowed
The page was made using a request method that is not supported by the page
406 Not Acceptable
The server can only generate a response that is not accepted by the client
407 Proxy Authentication Required
The client must first authenticate itself using a proxy
408 Request Timeout
The server has timed out waiting for the request
409 Conflict
The request could not be completed due to a conflict in the request
410 Gone
The requested page is no longer available
411 Length Required
"Content-Length" is not defined. The server will not accept the request without it
412 Precondition Failed
The precondition given in the request is evaluated as false by the server
413 Request Too Large
The server won't accept the request because the request entity is too large
414 Request-URI Too Long
The server won't accept the request because the URI is too long. Happens when you convert POST request to GET request with long query information
415 Unsupported Media Type
The server will not accept the request, because the media type is not supported
416 Range Not Satisfiable
The client requested part of the file, but the server could not provide that part
417 Expectation Failed
The server could not respond to the requests of the Expect request-header . field
5xx: Server Error
Notify
Describe
500 Internal Server Error
Generic error message, given when no specific message matches
501 Not Implemented
The server does not recognize the request method or is unable to make the request
502 Bad Gateway
The server is acting as a gateway or proxy and received an invalid response from the upstream server
503 Service Unavailable
Server is currently unavailable (overloaded or down)
504 Gateway Timeout
The server is acting as a gateway or proxy and is not receiving a timely response from the upstream server
505 HTTP Version Not Supported
The server does not support the HTTP protocol version used in the request
511 Network Authentication Required
Client needs authentication to have network access