HTTP (HyperText Transport Protocol) Status Codes and Messages

MIME:

Multipurpose Internet Mail Extensions is a specification that describes the transfer and format of media files. It is included in the header of an HTTP request. Because different media are transferred over the Web (images, text, video), the MIME header defines what needs to be linked to and transferred. Both browsers and web servers can be configured as to what MIME types they can transfer or accept.



Code Title Explanation Definition
1xx Informational Status codes in the 100 range inform the client (browser's computer) that the HTTP request is continuing. 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.
100 Continue The server has received the beginning of the request and the client should continue.
 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.
101 Switching Protocols Your computer has sent a request to a server to use a different connection protocol (ex., a newer HTTP protocol). The server has acknowledged that this is okay. The 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. 
2xx Successful Status codes in the 200 series indicate that the URL request was partially or completely successful. This class of status code indicates that the client's request was successfully received, understood, and accepted.
200 OK The request by your browser succeeded. The request has succeeded. The information returned with the response is dependent on the method used in the request.
201 Created The request successfully resulted in the creation of an additional resource and the text line should indicate the URL by which it should be known. The request has been fulfilled and resulted in a new resource being created. The newly created resource can be referenced by the URL(s) returned in the entity of the response, with the most specific URL 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.
202 Accepted The 202 response is to allow a server to accept a request for some other process without requiring that the connection to the server persist until the process is completed. 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.
203 Non-Authoritative Information Basically a 200 response, but where returned data may be from another server than the one originally contacted. The 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.
204 No Content Although the request was successful, there is no content to return. This is usually to permit additional input without a change to the user's view. The server has fulfilled the request but does not need to return an entity-body, and might want to return updated meta information. The response MAY include new or updated meta information in the form of entity-headers, which if present SHOULD be associated with the requested variant.
205 Reset Content Although the request was successful, content was not served. The server is awaiting further input from the user before proceeding. 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.
206 Partial Content This message might occur if a client has a partial copy of content in its cache and requests and update of missing content. This message indicates that the partial request succeeded. The server has fulfilled the partial GET request for the resource.
3xx Redirection Status codes in the 300 range indicate that additional client action is required. This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request. Note: Previous versions of the HTTP specification recommended a maximum of five redirections. Content developers should be aware that there might be clients that implement such a fixed limitation.
300 Multiple Choices The requested resource (e.g., a URL) could be one of several. The user will be provided with a list of possible choices, or the server could automatically redirect. 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.
301 Moved Permanently The requested resource has moved to a new URL. A 410 status code is returned if the new address is unavailable or not to be revealed. The requested resource has been assigned a new permanent URL and any future references to this resource SHOULD use one of the returned URLs.
302 Found The requested resource has moved, but the browser is not automatically redirected. Instead the new URL should be presented to the user. The requested resource resides temporarily under a different URL. Since the redirection might be altered on occasion, the client SHOULD continue to use the Request-URL for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.
303 See Other As with 302, the requested resource has moved, but if the request was a GET request, an automatic redirect by the browser is acceptable. The response to the request can be found under a different URL 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 URL is not a substitute reference for the originally requested resource.
304 Not Modified If a client has a partial copy of content in its cache and requests and update, but the document has not been modified since cached, the server responds with a 304 status code and does not send the content to the client. This allows updates of local cache information without fewer HTTP requests. If 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.
305 Use Proxy The requested resource (e.g., web page) must be accessed through the URL of the proxy server in this message. The requested resource MUST be accessed through the proxy given by the Location field.
306 (Unused) Not in use The 306 status code was used in a previous version of the specification, is no longer used, and the code is reserved.
307 Temporary Redirect As with 302 and 303, this code is for a moved resource. 303 and 307 were created as unambiguous alternatives to 302. 307 is a temporarily moved resource and thus the same URL should be continued to be used. The requested resource resides temporarily under a different URL. Since the redirection MAY be altered on occasion, the client SHOULD continue to use the Request-URL for future requests.
4xx Client Error Status codes in the 400 range are intended to indicate errors on the part of the browser or the machine on which it operates. The 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.
400 Bad Request The server did not understand your request. An improperly typed URL is usually the cause. If not that, there could be a problem with the document itself. The request could not be understood by the server due to malformed syntax.
401 Unauthorized This URL probably requires a username and password. Try submitting them again in case you made an error. If the password doesn't seem to work, contact the site administrator to resolve the problem. The request requires user authentication, typically a Username/Password credential pair. If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials.
402 Payment Required This is intended to return acceptable payment options. Not presently used. This code is reserved for future use.
403 Forbidden You tried to access a URL for which you don't have permission. If you usually can access this document, there might be a problem with the server. If so, contact the site administrator. The server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated.
404 Not Found This is probably the most common status code. Your browser cannot locate the document corresponding to the URL you entered. An improperly typed URL is usually the cause. The document may also have been moved. If you cannot find it elsewhere on the site, it may have been permanently removed. The server has not found anything matching the Request-URL. 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.
405 Method Not Allowed You may be attempting to run a script that is not supported. Some ISPs do not allow scripts on their servers, which could result in this status code. For an explanation of methods in HTTP headers see this page of the HTTP/1.1 protocol The method specified in the Request-Line is not allowed for the resource identified by the Request-URL.
406 Not Acceptable It's possible you have requested a page that contains files which your browser has indicated to the server that it cannot accept, for example, a multimedia file that your browser cannot process. Your browser sends information about what files it can accept to the server (in the HTTP header) as part of a request. You might check the preferences settings of your browser to see if there are file types it is not accepting. The 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.
407 Proxy Authentication Required There is a proxy server between your client and the server you are requesting the page from that requires a username and password. This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.
408 Request Timeout The request took longer than allowed to complete. Try the request again. If this error continues to appear, try waiting a few hours before repeating the request The 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.
409 Conflict Conflicts are likely to occur where an inappropriate alteration of the resource is being attempted. The 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.
410 Gone A 410 status code is returned if the new address is altogether unavailable or the server admin does not want to reveal it. The requested resource is no longer available at the server and no forwarding address is known. This condition is expected to be considered permanent.
411 Length Required Your client did not define the length of the requested content in the request header. The server refuses to accept the request without a defined Content-Length.
412 Precondition Failed The header of the request specified information about acceptable files that is not applicable to the requested file. The 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 meta information (header field data) and thus prevent the requested method from being applied to a resource other than the one intended.
413 Request Entity Too Large The content of the request is more than the server can process. The request may have included a message body, which is not always permissible. The 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.
414 Request-URL Too Long Since a POST request allows for an unlimited amount of data to be sent to a server by tagging it on to the request, if the request were converted to a GET request this error could result. Additionally, since a GET request allows for appending of search or form data in the header, the URL created could be longer than acceptable. The server is refusing to service the request because the Request-URL 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 URL "black hole" of redirection (e.g., a redirected URL 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-URL.
415 Unsupported Media Type There may have been an error in the MIME type indicated in the request header, i.e., your browser might have requested an image file, when in fact the requested file is an application. The 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.
416 Requested Range Not Satisfiable Your browser, which sends information on acceptable file size as part of its request, may have requested a file that does not fit these parameters. See the HTTP protocol for more information. A server SHOULD return a response with this status code if a request included a Range request-header field, 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.
417 Expectation Failed The Expect request-header field is used to indicate that particular server behaviors are required by the client. The server could not execute these expectations. The expectation given in an Expect request-header field 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.
5xx Server Error Status codes in the 500 range indicate that an error occurred with the server that you are trying to obtain a file from. Response 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.
500 Internal Server Error There is an internal server error on the site you are trying to contact. Unfortunately, there's nothing you can do other than contact the site administrator. The server encountered an unexpected condition which prevented it from fulfilling the request.
501 Not Implemented You've asked the server to do something it can't. The server in question may need to be upgraded. 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 you contacted for a document had to contact another server to obtain it. The server you first contacted received an error from the second server. The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request.
503 Service Unavailable The server you're trying to access is over tasked at the moment and it can't process your request. The server may be down for maintenance, or there may just be too many users on the site at the moment. The 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.
Note: The existence of the 503 status code does not imply that a must use it when becoming overloaded. Some servers may wish to simply refuse the connection.
504 Gateway Timeout Your modem or Internet connection has just hung up on you. There are several possible reasons for this. The most likely is that your connection has been inactive longer than allowed (the time limit will usually be set by your ISP). It could also be a server or network problem. The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URL (e.g. HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed to access in attempting to complete the request.
Note: Some deployed proxies are known to return 400 or 500 when DNS lookups time out.
505 HTTP Version Not Supported Your browser may have made a request using HTTP 1.1, whereas the server you made the request to supports only up to HTTP 1.0. This may occur when a proxy server sends along a request with a different version number. The server does not support, or refuses to support, the HTTP protocol version that was used in the request message.