400 The request could not be parsed.
401.1 Unauthorized: Access is denied due to invalid credentials.
401.2 Unauthorized: Access is denied because the server is configured to use an alternate authentication method.
401.3 Unauthorized: Access is denied due to ACL settings on the requested resource.
401.4 Unauthorized: The filter installed on the web server failed to authorize.
401.5 Unauthorized: ISAPI/CGI application authorization failed.
401.7 Unauthorized: Access denied due to URL authorization policy on the web server.
403 Forbidden: Access is denied.
403.1 Forbidden: Execution access is denied.
403.2 Forbidden: Read access denied.
403.3 Forbidden: Write access denied.
403.4 Forbidden: SSL is required to view this resource.
403.5 Forbidden: SSL 128 is required to view this resource.
403.6 Forbidden: The client's IP address was denied.
403.7 Forbidden: SSL client certificate required.
403.8 Forbidden: The client's DNS name was denied.
403.9 Forbidden: Too many clients trying to connect to the web server.
403.10 Forbidden: The web server is configured to deny access to execute.
403.11 Forbidden: Password changed.
403.12 Forbidden: Client certificate access is denied by the server certificate mapper.
403.13 Forbidden: The client certificate has been revoked on the web server.
403.14 Forbidden: Directory listing denied on web server.
403.15 Forbidden: The web server has exceeded the client access license limit.
403.16 Forbidden: The client certificate is malformed or not trusted by the web server.
403.17 Forbidden: The client certificate has expired or is not yet valid.
403.18 Forbidden: The requested URL cannot be executed in the current application pool.
403.19 Forbidden: Unable to perform CGI for client in this application pool.
403.20 Forbidden: Passport login failed.
404 File or directory not found.
404.1 File or directory not found: The website cannot be accessed on the requested port.
Note that 404.1 errors only appear on computers with multiple IP addresses. IIS returns a 404.1 HTTP error if a client request is received on a specific IP address/port combination, and the IP address is not configured to listen on that specific port. For example, if a computer has two IP addresses and only one of the IP addresses is configured to listen on port 80, any request that the other IP address receives from port 80 will cause IIS to return a 404.1 error. The error should only be set at this service level, as it will only be returned to the client when multiple IP addresses are used on the server.
404.3 File or directory not found: MIME mapping policy prohibits the request.
405 The HTTP action used to access the page is not permitted.
406 The client browser does not accept the MIME type of the requested page.
407 Web server requires initial proxy authentication.
410 File deleted.
412 The precondition set by the client failed while evaluating on the web server.
414 The request URL is too large to be accepted on the web server.
500 Internal Server Error.
500.11 Server Error: The application on the web server is shutting down.
500.12 Server Error: The application on the web server is restarting.
500.13 Server Error: The web server is too busy.
500.14 Server Error: Invalid application configuration on server.
500.15 Server Error: Direct request to GLOBAL.ASA is not allowed.
500.16 Server Error: Incorrect UNC authorization credentials.
500.17 Server Error: URL authorization store could not be found.
500.18 Server Error: URL authorization store could not be opened.
500.19 Server Error: The data for this file is not configured correctly in the metabase.
500.20 Server Error: URL authoritative domain could not be found.
500 100 Internal Server Error: ASP error.
501 The configuration specified by the header value was not executed.
502 The web server received an invalid response while acting as a gateway or proxy server.
504 Gateway Time-out error solution