HTTP Response Codes

Below is a summary of what the HTTP Response Codes mean. For more in-depth information, see section 10 of RFC 2616 (which defines what the reponse codes mean).

Authors should pay special attention to 400s and 500s, since these mean that the user did not successfully get to the page. 300s mean that the user was redirected, so the link might be changing. 600s generally mean that there was a problem with the URL, so the Link Checker couldn't figure out how to check it.

1xx: Informational

These reponse codes indicate a provisional response that should be followed by another response.

100 Continue The server has not rejected the initial part of the request, and the client should continue.

101 Switching Protocols The server agrees with the client's request to change protocols.

2xx Successful

These reponse codes indicate that the client's request was successfully received, understood, and accepted.

200 OK The request has succeeded.

201 Created The request has been fulfilled and resulted in a new resource being created.

202 Accepted The request has been accepted for processing, but the processing has not been completed.

203 Non-Authoritative Information The returned headers are not definitive, but are gathered from a local or a third-party copy.

204 No Content The server has fulfilled the request but does not need to return any output.

205 Reset Content The server has fulfilled the request and the client should reset the document view (primarily intended to make data-entry easier).

206 Partial Content The server has fulfilled the partial GET request for the resource.

3xx: Redirection

These response codes indicate that the client was redirected to another URI, or that further action needs to be taken by the user agent in order to fulfill the request.

300 Multiple Choices There are several resources that match this request, and the client was redirected to one of them.

301 Moved Permanently The requested resource has been assigned a new permanent URI and any future references to this resource should use the new URI.

302 Found The requested resource resides temporarily under a different URI. Since the redirection might be altered, continue to use the old URI.

303 See Other The response to the request can be found under a different URI and should be retrieved from the new URI.

304 Not Modified The document has not been modified since the last request, and the locally cached copy should be used instead.

305 Use Proxy The requested resource must be accessed through a proxy.

306 (Unused) Used in a previous version of the protocol.

307 Temporary Redirect The requested resource resides temporarily under a different URI. Since the redirection may be altered on occasion, continue to use the current URI.

4xx: Client Errors

These response codes are intended for cases in which the client seems to have erred.

400 Bad Request The request could not be understood by the server due to malformed syntax.

401 Unauthorized The request requires user authentication.

402 Payment Required This code is reserved for future use.

403 Forbidden The server understood the request, but is refusing to fulfill it. Typically due to file access permissions on the server.

404 Not Found The server has not found anything matching the URI.

405 Method Not Allowed The request method is not allowed. Typically when trying to execute a normal document or display a script.

406 Not Acceptable According to the client's request, it isn't capable of handling the response.

407 Proxy Authentication Required This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.

408 Request Timeout The client did not produce a request within the time that the server was prepared to wait.

409 Conflict The request could not be completed due to a conflict with the current state of the resource. Typically only seen with clients that can manage files on the remote server.

410 Gone The requested resource is no longer available at the server and no forwarding address is known.

411 Length Required The server refuses to accept the request without a defined Content-Length header.

412 Precondition Failed The precondition given in one or more of the header fields failed when it was tested on the server.

413 Request Entity Too Large The server is refusing to process a request because the request entity is larger than the server is willing or able to process.

414 Request-URI Too Long The server is refusing to service the request because the requested URI is too long.

415 Unsupported Media Type The server is refusing to service the request because the client does not support the response format.

416 Requested Range Not Satisfiable The server could not find the range specified in the Range header.

417 Expectation Failed The server could not meet the expectation given in the Expect header.

5xx: Server Errors

These response codes indicate cases in which the server is aware that it has erred or is incapable of performing the request.

500 Internal Server Error The server encountered an unexpected condition which prevented it from fulfilling the request.

501 Not Implemented The server does not support the functionality required to fulfill the request.

502 Bad Gateway The server is a gateway or proxy and received an invalid response from the upstream server it accessed in attempting to fulfill the request.

503 Service Unavailable The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.

504 Gateway Timeout The server is a gateway or proxy and did not receive a timely response from the upstream server.

505 HTTP Version Not Supported The server does not support, or refuses to support, the HTTP protocol version that was used in the request.

6xx: Internal Errors

These response codes indicate that an error occurred in the link checking program itself (these are unofficial error codes used to report problems).

600 Malformed URI The link checking program was not able to parse the URI. This means that the URI was either empty, or not a valid URI (e.g. "Ask at S&E Reference Desk").

601 Connection Timed Out The server did not respond before the connection timed out.

602 Unknown Error Some other error occurred in contacting the server, making the request, or parsing the response. This could be due to a mangled or incorrectly formatted response from the server.

603 Could Not Parse Reply The reply from the server could not be parsed. This could indicate a malformed response, or a non-numerical response code.

604 Protocol Not Supported This URI uses a protocol that is not currently supported by the linkchecker program. The linkchecker currently only supports http, so ftp, https, gopher, etc. are not supported. Also, some protocols (such as mailto://) cannot be checked.

1xx: Informational These reponse codes indicate a provisional response that should be followed by another response.
100	Continue	The server has not rejected the initial part of the request, and the client should continue.
101	Switching Protocols	The server agrees with the client's request to change protocols.
2xx Successful These reponse codes indicate that the client's request was successfully received, understood, and accepted.
200	OK	The request has succeeded.
201	Created	The request has been fulfilled and resulted in a new resource being created.
202	Accepted	The request has been accepted for processing, but the processing has not been completed.
203	Non-Authoritative Information	The returned headers are not definitive, but are gathered from a local or a third-party copy.
204	No Content	The server has fulfilled the request but does not need to return any output.
205	Reset Content	The server has fulfilled the request and the client should reset the document view (primarily intended to make data-entry easier).
206	Partial Content	The server has fulfilled the partial GET request for the resource.
3xx: Redirection These response codes indicate that the client was redirected to another URI, or that further action needs to be taken by the user agent in order to fulfill the request.
300	Multiple Choices	There are several resources that match this request, and the client was redirected to one of them.
301	Moved Permanently	The requested resource has been assigned a new permanent URI and any future references to this resource should use the new URI.
302	Found	The requested resource resides temporarily under a different URI. Since the redirection might be altered, continue to use the old URI.
303	See Other	The response to the request can be found under a different URI and should be retrieved from the new URI.
304	Not Modified	The document has not been modified since the last request, and the locally cached copy should be used instead.
305	Use Proxy	The requested resource must be accessed through a proxy.
306	(Unused)	Used in a previous version of the protocol.
307	Temporary Redirect	The requested resource resides temporarily under a different URI. Since the redirection may be altered on occasion, continue to use the current URI.
4xx: Client Errors These response codes are intended for cases in which the client seems to have erred.
400	Bad Request	The request could not be understood by the server due to malformed syntax.
401	Unauthorized	The request requires user authentication.
402	Payment Required	This code is reserved for future use.
403	Forbidden	The server understood the request, but is refusing to fulfill it. Typically due to file access permissions on the server.
404	Not Found	The server has not found anything matching the URI.
405	Method Not Allowed	The request method is not allowed. Typically when trying to execute a normal document or display a script.
406	Not Acceptable	According to the client's request, it isn't capable of handling the response.
407	Proxy Authentication Required	This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.
408	Request Timeout	The client did not produce a request within the time that the server was prepared to wait.
409	Conflict	The request could not be completed due to a conflict with the current state of the resource. Typically only seen with clients that can manage files on the remote server.
410	Gone	The requested resource is no longer available at the server and no forwarding address is known.
411	Length Required	The server refuses to accept the request without a defined Content-Length header.
412	Precondition Failed	The precondition given in one or more of the header fields failed when it was tested on the server.
413	Request Entity Too Large	The server is refusing to process a request because the request entity is larger than the server is willing or able to process.
414	Request-URI Too Long	The server is refusing to service the request because the requested URI is too long.
415	Unsupported Media Type	The server is refusing to service the request because the client does not support the response format.
416	Requested Range Not Satisfiable	The server could not find the range specified in the Range header.
417	Expectation Failed	The server could not meet the expectation given in the Expect header.
5xx: Server Errors These response codes indicate cases in which the server is aware that it has erred or is incapable of performing the request.
500	Internal Server Error	The server encountered an unexpected condition which prevented it from fulfilling the request.
501	Not Implemented	The server does not support the functionality required to fulfill the request.
502	Bad Gateway	The server is a gateway or proxy and received an invalid response from the upstream server it accessed in attempting to fulfill the request.
503	Service Unavailable	The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.
504	Gateway Timeout	The server is a gateway or proxy and did not receive a timely response from the upstream server.
505	HTTP Version Not Supported	The server does not support, or refuses to support, the HTTP protocol version that was used in the request.
6xx: Internal Errors These response codes indicate that an error occurred in the link checking program itself (these are unofficial error codes used to report problems).
600	Malformed URI	The link checking program was not able to parse the URI. This means that the URI was either empty, or not a valid URI (e.g. "Ask at S&E Reference Desk").
601	Connection Timed Out	The server did not respond before the connection timed out.
602	Unknown Error	Some other error occurred in contacting the server, making the request, or parsing the response. This could be due to a mangled or incorrectly formatted response from the server.
603	Could Not Parse Reply	The reply from the server could not be parsed. This could indicate a malformed response, or a non-numerical response code.
604	Protocol Not Supported	This URI uses a protocol that is not currently supported by the linkchecker program. The linkchecker currently only supports http, so ftp, https, gopher, etc. are not supported. Also, some protocols (such as mailto://) cannot be checked.