G.4.0- HTTP 1.1 Header Codes

Created by Brendan Doss.
Last Updated by Sarah Welna.

Public Categorized as Appendix G.

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HTTP 1.1 Header Codes

Code	Reason Phrase	Code		Reason Phrase
Group 1: Information		Group 4: Client Error
100	Continue	400	Bad Request
101	Switching Protocols	401	Unauthorized
Group 2: Success		402	Payment Required
200	OK	403	Forbidden
201	Created	404	Not Found
202	Accepted	405	Method Not Allowed
203	Non-Authoritative Information	406	Not Acceptable
204	No Content	407	Proxy Authentication Required
205	Reset Content	408	Request Time-out
206	Partial Content	409	Conflict
Group 3: Redirection		410	Gone
300	Multiple Choices	411	Length Required
301	Moved Permanently	412	Precondition Failed
302	Moved Temporarily	413	Request Entity Too Large
303	See Other	414	Request-URI Too Large
304	Not Modified	415	Unsupported Media Type
305	Use Proxy	Group 5: Server Error
		500	Internal Server Error
		501	Not Implemented
		502	Bad Gateway
		503	Service Unavailable
		504	Gateway Time-out
		505	HTTP Version not supported

Client error and server error codes – with default explanations as provided by Microsoft Internet Information Server – are listed below:

Error Code	Short Text	Explanation
400	Bad Request	Due to malformed syntax, the request could not be understood by the server. The client should not repeat the request without modifications.
401.1	Unauthorized. Logon Failed	This error indicates that the credentials passed to the server do not match the credentials required to log on to the server. Please contact the web server's administrator to verify that you have permission to access the requested resource.
401.2	Unauthorized: Logon Failed due to server configuration	This error indicates that the credentials passed to the server do not match the credentials required to log on to the server. This is usually caused by not sending the proper WWW-Authenticate header field. Please contact the web server's administrator to verify that you have permission to access to requested resource.
401.3	Unauthorized: Unauthorized due to ACL on resource	This error indicates that the credentials passed by the client do not have access to the particular resource on the server. This resource could be either the page or file listed in the address line of the client, or it could be another file on the server that is needed to process the file listed on the address line of the client. Please make a note of the entire address you were trying to access and then contact the web server's administrator to verify that you have permission to access the requested resource.
401.4	Unauthorized: Authorization failed by filter	This error indicates that the web server has a filter program installed to verify users connecting to the server. The authentication used to connect to the server was denied access by this filter program. Please make a note of the entire address you were trying to access and then contact the web server's administrator to verify that you have permission to access the requested resource.

Error Code	Short Text	Explanation
401.5	Unauthorized: Authorization failed by ISAPI/CGI app	This error indicates that the address on the web server you attempted to use has an ISAPI or CGI program installed that verifies user credentials before proceeding. The authentication used to connect to the server was denied access by this program. Please make a note of the entire address you were trying to access and then contact the web server's administrator to verify that you have permission to access the requested resource.
403.1	Forbidden: Execute Access Forbidden	This error can be caused if you try to execute a CGI, ISAPI, or other executable program from a directory that does not allow programs to be executed. Please contact the web server's administrator if the problem persists.
403.2	Forbidden: Read Access Forbidden	This error can be caused if there is no default page available and directory browsing has not been enabled for the directory, or if you are trying to display an HTML page that resides in a directory marked for Execute or Script permissions only. Please contact the web server's administrator if the problem persists.
403.3	Forbidden: Write Access Forbidden	This error can be caused if you attempt to upload to, or modify a file in, a directory that does not allow Write access. Please contact the web server's administrator if the problem persists.
403.4	Forbidden: SSL required	This error indicates that the page you are trying to access is secured with Secure Sockets Layer (SSL). In order to view it, you need to enable SSL by typing "https://" at the beginning of the address you are attempting to reach. Please contact the web server's administrator if the problem persists.
403.5	Forbidden: SSL 128 required	This error message indicates that the resource you are trying to access is secured with a 128-bit version of Secure Sockets Layer (SSL). In order to view this resource, you need a browser that supports this level of SSL. Please confirm that your browser supports 128-bit SSL security. If it does, then contact the web server's administrator and report the problem.
403.6	Forbidden: IP address rejected	This error is caused when the server has a list of IP addresses that are not allowed to access the site, and the IP address you are using is in this list. Please contact the web server's administrator if the problem persists.

Error Code	Short Text	Explanation
403.7	Forbidden: Client certificate required	This error occurs when the resource you are attempting to access requires your browser to have a client Secure Sockets Layer (SSL) certificate that the server recognizes. This is used for authenticating you as a valid user of the resource. Please contact the web server's administrator to obtain a valid client certificate.
403.8	Forbidden: Site access denied	This error can be caused if the web server is not servicing requests, or if you do not have permission to connect to the site. Please contact the web server's administrator.
403.9	Access Forbidden: Too many users are connected	This error can be caused if the web server is busy and cannot process your request due to heavy traffic. Please try to connect again later. Please contact the web server's administrator if the problem persists.
403.10	Access Forbidden: Invalid Configuration	There is a configuration problem on the web server at this time. Please contact the web server's administrator if the problem persists.
403.11	Access Forbidden: Password Change	This error can be caused if the user has entered the wrong password during authentication. Please refresh the page and try again. Please contact the web server's administrator if the problem persists.
403.12	Access Forbidden: Mapper Denied Access	Your client certificate map has been denied access to this web site. Please contact the site administrator to establish client certificate permissions. You can also change your client certificate and retry, if appropriate.
404	Not Found	The web server cannot find the file or script you asked for. Please check the URL to ensure that the path is correct. Please contact the server's administrator if this problem persists.
405	Method Not Allowed	The method specified in the Request Line is not allowed for the resource identified by the request. Please ensure that you have the proper MIME type set up for the resource you are requesting. Please contact the server's administrator if this problem persists.

Error Code	Short Text	Explanation
406	Not Acceptable	The resource identified by the request can only generate response entities that have content characteristics that are "not acceptable" according to the Accept headers sent in the request. Please contact the server's administrator if this problem persists.
407	Proxy Authentication Required	You must authenticate with a proxy server before this request can be serviced. Please log on to your proxy server, and then try again. Please contact the web server's administrator if this problem persists.
412	Precondition Failed	The precondition given in one or more of the Request-header fields evaluated to FALSE when it was tested on the server. The client placed preconditions on the current resource meta-information (header field data) to prevent the requested method from being applied to a resource other than the one intended. Please contact the web server's administrator if the problem persists.
414	Request-URI Too Long	The server is refusing to service the request because the Request-URI is too long. This rare condition is likely to occur only in the following situations: A client has improperly converted a POST request to a GET request with long query information. A client has encountered a redirection problem (for example, a redirected URL prefix that points to a suffix of itself). 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. Please contact the web server's administrator if this problem persists.
500	Internal Server Error	The web server is incapable of performing the request. Please try your request again later. Please contact the web server's administrator if this problem persists.

Error Code	Short Text	Explanation
501	Not Implemented	The web server does not support the functionality required to fulfill the request. Please check your URL for errors, and contact the web server's administrator if the problem persists.
502	Bad Gateway	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. Please contact the web server's administrator if the problem persists.