497 HTTP Request Sent to HTTPS Port
HTTP response status code 497 HTTP Request Sent to HTTPS Port is an unofficial client error specific to nginx and is returned by the server to indicate that a regular HTTP request has been sent to the HTTPS port.
Usage
When the 497 HTTP Request Sent to HTTPS Portstatus code is received, the HTTP request may be valid, but the server is unwilling to process it because it was sent to the HTTPS port. This is related to error 400 Bad Request. To solve this error, the HTTP request needs to be resubmitted either as an HTTPS request to the same port or as it was, but then to the HTTP port.
Note
Search engines like Google will not index a URL with 497 HTTP Request Sent to HTTPS Port response status, and consequently, URLs that have been indexed in the past but are now returning this HTTP status code will be removed from the search results.
Takeaway
The 497 HTTP Request Sent to HTTPS Port status code is a client error that is sent by the server when the client has sent an HTTP request to the HTTPS port.