The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless, protocol which can be used for many tasks beyond its use for hypertext, such as name servers and distributed object management systems, through extension of its request methods, error codes and headers. A feature of HTTP is the typing and negotiation of data representation, allowing systems to be built independently of the data being transferred.-- Internet Engineering Task Force
This class of status code indicates a provisional response, consisting only of the Status-Line and optional headers, and is terminated by an empty line. There are no required headers for this class of status code. Since HTTP/1.0 did not define any 1xx status codes, servers MUST NOT send a 1xx response to an HTTP/1.0 client except under experimental conditions.
The client SHOULD continue with its request. This interim response is used to inform the client that the initial part of the request has been received and has not yet 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.
Sample 100 - Continue ResponseThe server understands and is willing to comply with the client's request, via the Upgrade message header field, for a change in the application protocol being used on this connection. 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.
Sample 101 - Switching Protocols ResponseThis code indicates that the server has received and is processing the request, but no response is available yet.
Sample 102 - Processing ResponseThis status code is primarily intended to be used with the Link header to allow the user agent to start preloading resources while the server is still preparing a response.
Sample 103 - Early Hints ResponseThis class of status code indicates that the client's request was successfully received, understood, and accepted.
The request has succeeded. The information returned with the response is dependent on the method used in the request
Sample 200 - OK ResponseThe 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.
Sample 201 - Created ResponseThe 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.
Sample 202 - Accepted ResponseThe returned meta information 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 meta information 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).
Sample 203 - Non-Authoritative Information ResponseThe 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.
Sample 204 - No Content ResponseThe 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.
Sample 205 - Reset Content ResponseThe server has fulfilled the partial GET request for the resource. The request MUST have included a Range header field indicating the desired range, and MAY have included an If-Range header field to make the request conditional.
Sample 206 - Partial Content ResponseA Multi-Status response conveys information about multiple resources in situations where multiple status codes might be appropriate.
Sample 207 - Multi-Status ResponseUsed inside a DAV: propstat response element to avoid enumerating the internal members of multiple bindings to the same collection repeatedly.
Sample 208 - Multi-Status ResponseThe server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.
Sample 226 - IM Used ResponseThis class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request. The action required MAY be carried out by the user agent without interaction with the user if and only if the method used in the second request is GET or HEAD. A client SHOULD detect infinite redirection loops, since such loops generate network traffic for each redirection.
The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent- driven negotiation information is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that location.
Sample 300 - Multiple Choice ResponseThe requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Request-URI to one or more of the new references returned by the server, where possible. This response is cacheable unless indicated otherwise.
Sample 301 - Moved Permanently ResponseThe requested resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the client SHOULD continue to use the Request-URI for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.
Sample 302 - Found ResponseThe response to the request can be found under a different URI and SHOULD be retrieved using a GET method on that resource. This method exists primarily to allow the output of a POST-activated script to redirect the user agent to a selected resource. The new URI is not a substitute reference for the originally requested resource. The 303 response MUST NOT be cached, but the response to the second (redirected) request might be cacheable.
Sample 303 - See Other ResponseIf the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code. The 304 response MUST NOT contain a message-body, and thus is always terminated by the first empty line after the header fields.
Sample 304 - Not Modified ResponseThe requested resource MUST be accessed through the proxy given by the Location field. The Location field gives the URI of the proxy. The recipient is expected to repeat this single request via the proxy. 305 responses MUST only be generated by origin servers.
Sample 305 - Use Proxy ResponseThe 306 status code was used in a previous version of the specification, is no longer used, and the code is reserved.
Sample 306 - Unused ResponseThe requested resource resides temporarily under a different URI. Since the redirection MAY be altered on occasion, the client SHOULD continue to use the Request-URI for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.
Sample 307 - Temporary Redirect ResponseThis means that the resource is now permanently located at another URI, specified by the Location: HTTP Response header. This has the same semantics as the 301 Moved Permanently HTTP response code, with the exception that the user agent must not change the HTTP method used: If a POST was used in the first request, a POST must be used in the second request.
Sample 308 - Permanent Redirect ResponseThe 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD request, the server SHOULD include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes are applicable to any request method. User agents SHOULD display any included entity to the user.
The request could not be understood by the server due to malformed syntax. The client SHOULD NOT repeat the request without modifications.
Sample 400 - Bad Request ResponseThe request requires user authentication. The response MUST include a WWW-Authenticate header field (section 14.47) containing a challenge applicable to the requested resource. The client MAY repeat the request with a suitable Authorization header field (section 14.8). If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials. If the 401 response contains the same challenge as the prior response, and the user agent has already attempted authentication at least once, then the user SHOULD be presented the entity that was given in the response, since that entity might include relevant diagnostic information. HTTP access authentication is explained in "HTTP Authentication: Basic and Digest Access
Sample 401 - Unauthorized ResponseThe server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated. If the request method was not HEAD and the server wishes to make public why the request has not been fulfilled, it SHOULD describe the reason for the refusal in the entity. If the server does not wish to make this information available to the client, the status code 404 (Not Found) can be used instead.
Sample 403 - Forbidden ResponseThe server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address. This status code is commonly used when the server does not wish to reveal exactly why the request has been refused, or when no other response is applicable.
Sample 404 - Not Found ResponseThe method specified in the Request-Line is not allowed for the resource identified by the Request-URI. The response MUST include an Allow header containing a list of valid methods for the requested resource.
Sample 405 - Method Not Allowed ResponseThe resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.
Sample 406 - Not Acceptable ResponseThis code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy. The proxy MUST return a Proxy-Authenticate header field (section 14.33) containing a challenge applicable to the proxy for the requested resource. The client MAY repeat the request with a suitable Proxy-Authorization header field (section 14.34). HTTP access authentication is explained in "HTTP Authentication: Basic and Digest Access Authentication"
Sample 407 - Proxy Authentication Required ResponseThe client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time.
Sample 408 - Request Timeout ResponseThe request could not be completed due to a conflict with the current state of the resource. This code is only allowed in situations where it is expected that the user might be able to resolve the conflict and resubmit the request. The response body SHOULD include enough information for the user to recognize the source of the conflict. Ideally, the response entity would include enough information for the user or user agent to fix the problem; however, that might not be possible and is not required.
Sample 409 - Conflict ResponseThe requested resource is no longer available at the server and no forwarding address is known. This condition is expected to be considered permanent. Clients with link editing capabilities SHOULD delete references to the Request-URI after user approval. If the server does not know, or has no facility to determine, whether or not the condition is permanent, the status code 404 (Not Found) SHOULD be used instead. This response is cacheable unless indicated otherwise.
Sample 410 - Gone ResponseThe server refuses to accept the request without a defined Content- Length. The client MAY repeat the request if it adds a valid Content-Length header field containing the length of the message-body in the request message.
Sample 411 - Length Required ResponseThe precondition given in one or more of the request-header fields evaluated to false when it was tested on the server. This response code allows the client to place preconditions on the current resource metainformation (header field data) and thus prevent the requested method from being applied to a resource other than the one intended.
Sample 412 - Precondition Failed ResponseThe server is refusing to process a request because the request entity is larger than the server is willing or able to process. The server MAY close the connection to prevent the client from continuing the request.
Sample 413 - Payload Too Large ResponseThe server is refusing to service the request because the Request-URI is longer than the server is willing to interpret. This rare condition is only likely to occur when a client has improperly converted a POST request to a GET request with long query information, when the client has descended into a URI "black hole" of redirection (e.g., a redirected URI prefix that points to a suffix of itself), or when the server is under attack by a client attempting to exploit security holes present in some servers using fixed-length buffers for reading or manipulating the Request-URI.
Sample 414 - URI Too Long ResponseThe server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.
Sample 415 - Unsupported Media Type ResponseA server SHOULD return a response with this status code if a request included a Range request-header field (section 14.35), and none of the range-specifier values in this field overlap the current extent of the selected resource, and the request did not include an If-Range request-header field. (For byte-ranges, this means that the first- byte-pos of all of the byte-range-spec values were greater than the current length of the selected resource.)
Sample 416 - Requested Range Not Satisfiable ResponseThe expectation given in an Expect request-header field (see section 14.20) could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could not be met by the next-hop server.
Sample 417 - Expectation Failed ResponseThe server refuses the attempt to brew coffee with a teapot.
Sample 418 - I'm a teapot ResponseThe request was directed at a server that is not able to produce a response. This can be sent by a server that is not configured to produce responses for the combination of scheme and authority that are included in the request URI.
Sample 421 - Misdirected Request ResponseThe request was well-formed but was unable to be followed due to semantic errors.
Sample 422 - Unprocessable Entity ResponseThe request failed due to failure of a previous request.
Sample 424 - Failed Dependency ResponseIndicates that the server is unwilling to risk processing a request that might be replayed.
Sample 425 - Too Early ResponseThe server refuses to perform the request using the current protocol but might be willing to do so after the client upgrades to a different protocol. The server sends an Upgrade header in a 426 response to indicate the required protocol(s).
Sample 426 - Upgrade Required ResponseThe origin server requires the request to be conditional. Intended to prevent the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.
Sample 428 - Precondition Required ResponseThe user has sent too many requests in a given amount of time ("rate limiting").
Sample 428 - Too Many Requests ResponseThe server is unwilling to process the request because its header fields are too large. The request MAY be resubmitted after reducing the size of the request header fields.
Sample 431 - Request Header Fields Too Large ResponseThe user requests an illegal resource, such as a web page censored by a government.
Sample 451 - Unavailable For Legal Reasons ResponseResponse status codes beginning with the digit "5" indicate cases in which the server is aware that it has erred or is incapable of performing the request. Except when responding to a HEAD request, the server SHOULD include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. User agents SHOULD display any included entity to the user. These response codes are applicable to any request method.
The server encountered an unexpected condition which prevented it from fulfilling the request.
Sample 500 - Internal Server Error ResponseThe 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.
Sample 501 - Not Implemented ResponseThe server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request.
Sample 502 - Bad Gateway ResponseThe server is currently unable to handle the request due to a temporary overloading or maintenance of the server. The implication is that this is a temporary condition which will be alleviated after some delay. If known, the length of the delay MAY be indicated in a Retry-After header. If no Retry-After is given, the client SHOULD handle the response as it would for a 500 response.
Sample 503 - Service Unavailable ResponseThe server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URI (e.g. HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed to access in attempting to complete the request.
Sample 504 - Gateway Timeout ResponseThe server does not support, or refuses to support, the HTTP protocol version that was used in the request message. The server is indicating that it is unable or unwilling to complete the request using the same major version as the client, as described in section 3.1, other than with this error message. The response SHOULD contain an entity describing why that version is not supported and what other protocols are supported by that server.
Sample 505 - HTTP Version Not Supported ResponseThe server has an internal configuration error: transparent content negotiation for the request results in a circular reference.
Sample 506 - Variant Also Negotiates ResponseThe server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, and is therefore not a proper end point in the negotiation process.
Sample 507 - Insufficient Storage ResponseThe server detected an infinite loop while processing the request.
Sample 508 - Loop Detected ResponseFurther extensions to the request are required for the server to fulfill it.
Sample 510 - Not Extended ResponseThe 511 status code indicates that the client needs to authenticate to gain network access.
Sample 511 - Network Authentication Required Response