A 495 SSL Certificate Error is an nginx-specific code for: "Your client SSL certificate is expired, invalid, or was not signed by a trusted authority.".

How do I fix or troubleshoot a 495 Error?

Common steps include reloading the page in your browser, checking for typos in the URL, verifying server status, clearing browser cache or cookies, and contacting the website owner or server administrator if the error persists.

495 Error | Error-Message.Net

A 495 SSL Certificate Error is an internal status code used by nginx when a client presents an SSL/TLS certificate that fails cryptographic verification.

In environments utilizing mutual TLS (mTLS) or smart card authentication, the client must present a valid digital certificate to enter. If the certificate is expired, self-signed, revoked, or signed by an untrusted Certificate Authority (CA), nginx logs error 495.

Determining why

Your personal client certificate or smart card certificate has expired.
The server’s CA bundle (ssl_client_certificate) does not include the authority that issued your certificate.
The certificate chain sent by the browser is incomplete.

Steps you could possibly take:

Renew your client certificate - Contact your organization’s IT department or certificate authority to obtain a current, valid certificate.
If you are the server administrator:
- Verify the CA certificate bundle specified in the ssl_client_certificate directive.
- Adjust certificate revocation list (ssl_crl) verification settings.

Source: nginx Documentation - ngx_http_ssl_module