496 SSL Certificate Required
HTTP response status code 496 SSL Certificate Required is an unofficial client error specific to nginx and is returned by the server to indicate that the client has not presented the required certificate.
Usage
When the 496 SSL Certificate Required status code is received, the client has sent an HTTP request that does not include an SSL certificate, yet one is needed. This is related to error 400 Bad Request. To solve this error, the HTTP request needs to be resubmitted with a valid SSL certificate.
Note
Search engines like Google will not index a URL with 496 SSL Certificate Required 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 496 SSL Certificate Required status code is a client error that is sent by the server when the client submits an HTTP request that is lacking the required SSL certificate.