HTTP status codes reference

3xx codes (redirection)

List of the HTTP status codes used for the query redirection (3xx codes).

Code Error Description
300 Multiple choices

The requested URL corresponds to more than one resource, and the robot failed to determine to which page it refers (code 300 Multiple Choices).

Fix the headers and specify the resource correctly, the robot then will be able to index the page.

301 The resource moved permanently

The document isn't used by the server and link redirects to another page (code 301 Moved Permanently).

As the users won't see such documents, it doesn't make sense to show them in the search, so the robot doesn't index them. However the robot will index the redirect destination page.

302 Resource moved temporarily

The requested resource is temporarily located under another address (code 302 Found).

As the users won't see such documents, it doesn't make sense to show them in the search, so the robot doesn't index them. However the robot will index the redirect destination page.

303 See another resource.

The requested resource resides under a different URL and should be requested with the GET method (code 303 See Other). For the page to be in the search, it must respond with the 200 code.

304 Resource not modified

Code 304 Not Modified. Respond with this code if the page hasn't changed since the last visit by the robot. This will speed up indexing and reduce the traffic.

305 Use proxy

The requested resource can be accessed only through the proxy server specified in the Location header (code 305 Use Proxy).

307 Temporary redirection

The requested resource has been temporarily relocated to another address. Specify this address in Location (code 307 Temporary Redirect).

The 4xx codes (client error)

List of the HTTP status codes used for possible errors in the client's request (4xx codes).

Code Error Description
400 Bad request

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

401 Unauthorized request

A password is required to access the document or the user must be registered (code 401 Unauthorized).

402 Payment for the request is required

Internal error or server configuration error (code 402 Payment Required).

403 The access to the resource is forbidden.

The access to the document is forbidden (code403 Forbidden). To have the page indexed, allow access to it.

404 Resource not found

The document doesn't exist (code 404 Not Found). If you deleted a section of the site, you can use robots.txt to prevent the robot from accessing it. If such a page on the site never existed, ignore this error, perhaps someone put an incorrect link to your site.

405 Invalid method

The method defined in the request (Request-Line) can't be applied for the specified resource, so the robot couldn't index it (code 405 Method Not Allowed).

406 Unacceptable request

The required document exists, but the format is incorrect (the language or encoding is not supported by the robot). Code 406 Not Acceptable.

407 Proxy or firewall identification is required.

The proxy server requires registration (code 407 Proxy Authentication Required).

408 Request timed out

The site failed to complete the request within the specified time and the robot disconnected (code 408 Request Timeout).

409 Conflict

The request conflicts with another request or with the server configuration (code 409 Conflict).

410 Resource unavailable

The requested resource was permanently deleted from the site (code 410 Gone).

411 Length is required

The server refuses to accept the request without a certain Content-Length header (code 411 Length Required). Correct the headers on your server. The robot will be able to index the page next time.

412 Precondition processing failed

The server found a mismatch in one or more request header fields (a failure or an error in the precondition processing). Code 412 Precondition Failed.

413 The request body exceeds the allowed size

The server refuses to process the request because it is larger than the server can handle (code 413 Request Entity Too Large).

414 Request URI is too long

The server refuses to process the request, because the URI (Request-URI) requested by the robot is longer than the server can render (code 414 Request-URI Too Long).

415 Unsupported MIME type

The server refuses to process the request, because the request body has an unsupported format (code 415 Unsupported Media Type).

416 The range can't be processed

The server refuses to process the request, because the Range field in the request header contains an invalid byte range (code 416 Requested Range Not Satisfiable).

417 Failed while waiting

The server refuses to process the request, because the value of the Expect field in the request header is unexpected (code 417 Expectation Failed).

422 Unprocessable element

The server can't process one (or more) request element (code 422 Unprocessable Entity).

423 Blocked

The server refuses to process the request, because one of the required resources is blocked (code 423 Locked).

424 Incorrect dependency

The server refuses to process the request, because one of the dependent resources is blocked (code 424 Failed Dependency).

426 Upgrade required

The server requested connection upgrade to SSL, but the client doesn't support SSL (code 426 Upgrade Required).

5xx codes (server error)

List of the HTTP status codes used for possible server errors (5xx codes).

Code Error Description
500 Internal server error.

The server encountered an unexpected condition that doesn't allow it to complete the request (code 500 Internal Server Error).

501 Method not supported

The server doesn't support the functionality required to execute the request (code 501 Not Implemented). This response means the server doesn't recognize the request method and can't provide it for any resource.

502 Gateway error

The server acting as a gateway or proxy server received an invalid response from an inbound server it accessed while attempting to fulfill the request (code 502 Bad Gateway).

503 Service unavailable

An error occurred due to temporary overload or disconnection for server maintenance (code 503 Service Unavailable).

504 Gateway timeout

The server, while acting as a gateway or proxy, did not receive a timely response from an upstream server it needed to access in order to complete the request (code 504 Gateway Timeout).

505 HTTP version isn't supported

The server doesn't support or refuses to support the version of the HTTP protocol used in the robot request message (code 505 HTTP Version Not Supported).

507 Insufficient space

The server can't process the request due to the lack of the disk space (code 507 Insufficient Storage).

510 Not extended

The server can't process the request because the requested extension is not supported (code 510 Not Extended).