HTTP Error 403-Access prohibited

This problem occurs during debugging. The original error is simple:

When IIS is installed by default, the "enable default document" list does not contain index. ASP, but now many websites use this file as the starting page, so remember to add it. Otherwise, "HTTP Error 403-Access prohibited" will appear ".

There are many reasons for "HTTP Error 403". This is only one reason.

Appendix:

400 the request cannot be parsed.

401.1 unauthorized: access is denied due to invalid creden.

401.2 unauthorized access: access is denied due to server configuration preference to use alternative authentication methods.

401.3 unauthorized: access to requested resources is denied due to ACL settings.

401.4 unauthorized: the filter installed on the Web server fails to be authorized.

401.5 unauthorized: The ISAPI/cgi application fails to be authorized.

401.7 unauthorized: access is denied due to the URL Authorization Policy on the Web server.

403 Access prohibited: access is denied.

403.1 Access prohibited: Access denied.

403.2 Access prohibited: Read access is denied.

403.3 Access prohibited: Write access is denied.

403.4 forbidden access: use SSL to view the resource.

403.5 forbidden access: use SSL 128 to view the resource.

403.6 Access prohibited: the client's IP address is denied.

403.7 Access prohibited: An ssl client certificate is required.

403.8 Access prohibited: the client's DNS name is denied.

403.9 Access prohibited: too many clients attempt to connect to the web server.

403.10 Access prohibited: the Web server is configured to reject access requests.

403.11 Access prohibited: the password has been changed.

403.12 Access prohibited: the server certificate er rejects access to the client certificate.

403.13 Access prohibited: the client certificate has been revoked on the Web server.

403.14 forbidden access: the directory list has been denied on the Web server.

403.15 Access prohibited: the Web server has exceeded the Client Access License limit.

403.16 Access prohibited: the client certificate format is incorrect or is not trusted by the Web server.

403.17 Access prohibited: the client certificate has expired or has not yet taken effect.

403.18 Access prohibited: the requested URL cannot be executed in the current application pool.

403.19 Access prohibited: CGI cannot be executed for the client in the application pool.

403.20 Access prohibited: Passport Logon Failed.

404 the file or directory cannot be found.

404.1 file or directory not found: the website cannot be accessed on the requested port.

Note that the 404.1 error only appears on a computer with multiple IP addresses. If a client request is received on a specific IP Address/Port Combination and the IP address is not configured to listen on the specific port, IIS returns the 404.1 HTTP Error. For example, if a computer has two IP addresses and only one of them is configured to listen on port 80, any request received from port 80 from another IP address will cause IIS to return the 404.1 error. This error should be set only at this service level, because it is returned to the client only when multiple IP addresses are used on the server.