Basically covers all the issues
Invalid HTTP 400– request
HTTP 401.1– not authorized: Logon failed
HTTP 401.2– not authorized: Login failed due to server configuration problem
HTTP 401.3–acl prohibit access to resources
HTTP 401.4– not authorized: Authorization denied by filter
HTTP 401.5– not authorized: ISAPI or CGI authorization failed
HTTP 403– Disable Access
HTTP 403– access to Internet Service Manager is limited to Localhost
HTTP 403.1 Forbidden: Disable executable access
HTTP 403.2– Forbidden: Disable Read access
HTTP 403.3– Forbidden: write-Access Forbidden
HTTP 403.4– Forbidden: SSL Required
HTTP 403.5– Forbidden: SSL 128 Required
HTTP 403.6– Forbidden: IP address denied
HTTP 403.7– Forbidden: Require client certificate
HTTP 403.8– Forbidden: Prohibit site access
HTTP 403.9– Forbidden: Too many users are connected
HTTP 403.10– Forbidden: Invalid configuration
HTTP 403.11– Forbidden: Password change
HTTP 403.12– Forbidden: Mapper denied access
HTTP 403.13– Forbidden: Client certificate has been revoked
HTTP 403.15– Forbidden: Too many client access licenses
HTTP 403.16– Forbidden: Client certificate is untrusted or invalid
HTTP 403.17– Forbidden: Client certificate has expired or has not been effective HTTP 404.1-
Unable to find Web site
HTTP 404-File not Found
HTTP 405– Resource is forbidden
HTTP 406– Not acceptable
HTTP 407– Proxy Authentication Required
HTTP 410– is never available
HTTP 412– Prerequisites Failed
HTTP 414– request –uri too long
HTTP 500– Internal Server error
HTTP 500.100– Internal Server error –asp error
HTTP 500-11 Server shutdown
HTTP 500-12 Application Restart
HTTP 500-13– Server Too busy
Invalid HTTP 500-14– application
HTTP 500-15– does not allow request Global.asa
Error 501– Not implemented
HTTP 502– Gateway Error
Reprinted from: http://www.cnblogs.com/nuke/archive/2012/06/04/2534346.html
"Go" 404, 500, 502 and other HTTP status code introduction