HTTP Codes - Meaning of status codes

HTTP status codes are returned by a server to a client that establishes or attempts to establish a connection. When a problem occurs, this code is accompanied by information on the causes of the problem.

The table below gives the meaning of all HTTP codes and their involvement.

The WebDav extension sometimes mentioned is a HTTP protocol added to help managing files remotely and exchanging files between the client and the server. It is defined by the IETF.

 

Request in progress

100
Continue. Request initiated and not rejected. The client can continue.
101
Switching Protocols. The server reports having received a request to change protocol and it is accepted.
102
In processing. Makes clear that the server is active and not inaccessible.(WebDav Extension).
 
 

Request processed

200
Request completed successfully.The page is found and displayed.
201
Created.Establishing a link between the client and the server in the form of URI on a newly created resource.
202
Accepted.The request is received and accepted but not yet processed..
203
Non-Authoritative information.The server response provides information that does not certify it. It could come from a third-party source.
204
No content.No information to return from the server.
205
Reset content. Request processed, the client must reset the source of the request.In the case of a form, it must be cleared before another request.
206
Partial content.Only part of the content is returned.(This may be due to limitation of resources). A Range header must have been included by the user.
207
Multiple statements for the answer.(WebDav Extension).
210
Different contents between the server and the client.(WebDav Extension).
 
 

Redirections
300
Multiple choice.The server has different answers, so it must return a list of resources with their location.
301
Moved permanently.To be used when a file is renamed or moved, and a new URL must be provided.The old URL will be ignored by robots.
302
Moved temporarily. A new URL is provided but robots return to the original URL.
303
See other location.This code is returned when the resource can be retrieved atto another address and a GET method must be used to obtain it. The client is redirected if the method is GET.
304
Unmodified.The page has not changed since the last request, and no content is returned.This assumes that the server is configured to provide a If-modified-since header.
Essential for robots of search engines.
305
Use a proxy.Response from the server asking to recover the document on a proxy server whose address is provided.
307
Temporary redirect.The request is redirected to another address as 302.
 
 

Client error or access denied

400
Bad request.The server does not recognize the command syntax.
401
Unauthorized.Authentication required. Connections refused unless a valid password is furnished.
402
Payment required. Future use.
403
Forbidden.Access is prohibited or it is prohibited to a specified robot (for the server and not by robots.txt).
404
Not found.The page does not exist.This may be due to an incorrect spelling, different cases on Unix, or a change of address.
405
Method of request not allowed.
406
Not acceptable.The server can not provide the type of document requested.
407
Proxy authentication required.The connection is refused because the client needs to connect only through a proxy server that is indicated in the response.
408
Timeout. Expiration of time allocated to a request.
409
Conflict.The request contains a request that conflicts with the state of the resource. The information on the causes are provided with the error code. Occurs with the PUT method.
410
Gone.As 404 but means that the page not found was there before. Google recommends its use rather than 404 when the page is missing forever.
411
Length required.The server does not accept the request if the Content-Length is not specified.
412
Precondition not met.The request is accompanied by conditions that the server can not fulfill.
413
Volume asked too high.The server can not provide a document of this size.
414
Request-URI too long.The size of the URI sent to the server exceeds the number of characters allowed. Occurs whan a POST is converted to GET.
415
Unsupported media type.The client requests a document type that the server does not support.
416
Requested range not satisfiable. The request specifies the Range (ex 200-10000) and the size of the resource is not included in this range.
417
Expectation failed .The request contains a field Expect and the server can not meet it.The definition of this field is vague.
422
The request contains an entity that the server can not handle.(WebDav Extension).
423
Locked.The page is locked and will not be transmitted.(WebDav Extension).
424
Failure of the method used by the request.(WebDav Extension).
451

The site is blocked for legal reasons. The provider then returns this code, added in 2015. (The code is a reference to the novel Fahrenheit 451).

 
 

Server errors
500
Internal Server Error.The request is not processed.
501
Not implemented.The server does not recognize the nature of the request, the method used, for example.
502
Bad gateway.When the server acts as a proxy or intermediary and that the other server not responding.
503
Service unavailable.Temporary problem due to overloading or other server problem including maintenance.
504
Gateway timeout. Waiting time from the other server exceeded, when the server asked plays the role of gateway.
505
HTTP Version not supported.The protocol used is too recent or not handled.
507
Space on the server insufficient to accomplish the client's request.(WebDav Extension).
509
Non-standard code but may be used by servers when exceeding quota.

References and tools