The following are standard HTTP status codes:

Http status code with certificate: [status code]: The “with certificate” indicates the HTTPS branch.

Http status code: [status code]: Indicates the HTTP branch that does not handle certificates.

Status Codes

• 403, “forbidden”: Usually indicates a certificate issue.
• 407, “Proxy authentication required”: Indicates the need to enable the use of a proxy.
• 500, server error: Look in the diagnostic log or Windows logs, or enable logging in IIS.