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Web Access Errors

Web Errors - Michael Robinson

When a browser requests a service from a web server, an error might occur.

This is a list of HTTP status messages that might be returned:

Source


The 100 Section = Information

Error Name Error Type
100 Continue



The client SHOULD continue with its request. This response informs the client that the initial part of the request has been received and has not been rejected by the server. The client SHOULD continue by sending the remainder of the request or, if the request has already been completed, ignore this response. The server MUST send a final response after the request has been completed.

101 Switching Protocols



The server will switch protocols to those defined by the response's Upgrade header field immediately after the empty line which terminates the 101 response.



The 200 Section = Successful

Error Name Error Type
200 OK







The request has succeeded. The information returned with the response is dependent on the method used in the request, for example:
- GET an entity corresponding to the requested resource is sent in the response;
- HEAD the entity-header fields corresponding to the requested resource are sent in the response without any message-body;
- POST an entity describing or containing the result of the action;
- TRACE an entity containing the request message as received by the end server.

201 Created












The request has been fulfilled and resulted in a new resource being created. The newly created resource can be referenced by the URI(s) returned in the entity of the response, with the most specific URI for the resource given by a Location header field. The response SHOULD include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. The origin server MUST create the resource before returning the 201 status code. If the action cannot be carried out immediately, the server SHOULD respond with 202 (Accepted) response instead.
A 201 response MAY contain an ETag response header field indicating the current value of the entity tag for the requested variant just created, see section 14.19.

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202 Accepted












The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually be acted upon, as it might be disallowed when processing actually takes place. There is no facility for re-sending a status code from an asynchronous operation such as this.

The 202 response is intentionally non-committal. Its purpose is to allow a server to accept a request for some other process (perhaps a batch-oriented process that is only run once per day) without requiring that the user agent's connection to the server persist until the process is completed. The entity returned with this response SHOULD include an indication of the request's current status and either a pointer to a status monitor or some estimate of when the user can expect the request to be fulfilled.

203 Non-Authoritative Information




The returned metainformation in the entity-header is not the definitive set as available from the origin server, but is gathered from a local or a third-party copy. The set presented MAY be a subset or superset of the original version. For example, including local annotation information about the resource might result in a superset of the metainformation known by the origin server. Use of this response code is not required and is only appropriate when the response would otherwise be 200 (OK).
204 No Content




The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation. The response MAY include new or updated metainformation in the form of entity-headers, which if present SHOULD be associated with the requested variant.

If the client is a user agent, it SHOULD NOT change its document view from that which caused the request to be sent. This response is primarily intended to allow input for actions to take place without causing a change to the user agent's active document view, although any new or updated metainformation SHOULD be applied to the document currently in the user agent's active view.

The 204 response MUST NOT include a message-body, and thus is always terminated by the first empty line after the header fields.

205 Reset Content




The server has fulfilled the request and the user agent SHOULD reset the document view which caused the request to be sent. This response is primarily intended to allow input for actions to take place via user input, followed by a clearing of the form in which the input is given so that the user can easily initiate another input action. The response MUST NOT include an entity.

206 Partial Content




The server has fulfilled the partial GET request for the resource. The request MUST have included a Range header field (section 14.35) indicating the desired range, and MAY have included an If-Range header field (section 14.27) to make the request conditional.

The response MUST include the following header fields:
- Either a Content-Range header field (section 14.16) indicating
the range included with this response, or a multipart/byteranges
Content-Type including Content-Range fields for each part. If a
Content-Length header field is present in the response, its
value MUST match the actual number of OCTETs transmitted in the
message-body.
- Date
- ETag and/or Content-Location, if the header would have been sent
in a 200 response to the same request
- Expires, Cache-Control, and/or Vary, if the field-value might
differ from that sent in any previous response for the same variant
If the 206 response is the result of an If-Range request that used a strong cache validator (see section 13.3.3), the response SHOULD NOT include other entity-headers. If the response is the result of an If-Range request that used a weak validator, the response MUST NOT include other entity-headers; this prevents inconsistencies between cached entity-bodies and updated headers. Otherwise, the response MUST include all of the entity-headers that would have been returned with a 200 (OK) response to the same request.

A cache MUST NOT combine a 206 response with other previously cached content if the ETag or Last-Modified headers do not match exactly, see 13.5.4.

A cache that does not support the Range and Content-Range headers MUST NOT cache 206 (Partial) responses.




The 300 Section = Redirection

Error Name Error Type
300 Multiple Choices




The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent- driven negotiation information (section 12) is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that location.

Unless it was a HEAD request, the response SHOULD include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose the one most appropriate. The entity format is specified by the media type given in the Content- Type header field. Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice MAY be performed automatically. However, this specification does not define any standard for such automatic selection.

If the server has a preferred choice of representation, it SHOULD include the specific URI for that representation in the Location field; user agents MAY use the Location field value for automatic redirection. This response is cacheable unless indicated otherwise.

301 Moved Permanently




The requested page has moved to a new URL 

302 Found




The requested page has moved temporarily 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 last requested

306 Switch Proxy




No longer used

307 Temporary Redirect




The requested page has moved temporarily to a new URL
308 Resume Incomplete




Used in the resumable requests proposal to resume aborted PUT or POST requests



The 400 Section = Client Error

Error Name Error Type
400 Bad Request




The request cannot be fulfilled due to bad syntax
401 Unauthorized




The request was a legal request, but the server is refusing to respond to it. For use when authentication is possible but has failed or not yet been provided
402 Payment Required




Reserved for future use
403 Forbidden




The request was a legal request, but the server is refusing to respond to it
404 Not Found




The requested page could not be found but may be available again in the future
405 Method Not Allowed




A request was made of a page using a request method not supported by that 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 with the proxy
408 Request Timeout




The server timed out waiting for the request
409 Conflict




The request could not be completed because of a conflict in the request
410 Gone




The requested page is no longer available
411 Length Required




The "Content-Length" is not defined. The server will not accept the request without it
412 Precondition Failed




The precondition given in the request evaluated to false by the server
413 Request Entity Too Large




The server will not accept the request, because the request entity is too large
414 Request-URI Too Long




The server will not accept the request, because the URL is too long. Occurs when you convert a POST request to a GET request with a long query information
415 Unsupported Media Type




The server will not accept the request, because the media type is not supported
416 Requested Range Not Satisfiable




The client has asked for a portion of the file, but the server cannot supply that portion
417 Expectation Failed




The server cannot meet the requirements of the Expect request-header field



The 500 Section = Server Error

Error Name Error Type
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. This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource.

502 Bad Gateway




The server was acting as a gateway or proxy and received an invalid response from the upstream server
503 Service Unavailable




The server is currently unavailable (overloaded or down)
504 Gateway Timeout




The server was acting as 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 the HTTP protocol version used in the request
511 Network Authentication Required




The client needs to authenticate to gain network access



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