Comprehensive Guide to Resolving
HTTP Error 495

The 495 error code, "SSL Certificate Error," is specific to Nginx, an open-source web server. This error occurs when a client attempts to connect to the server using an invalid SSL certificate. Common causes include expired certificates, untrusted certificates issued by a non-trusted Certificate Authority (CA), or misconfigured certificates with incorrect chains or mismatched domain names.

The 495 status code indicates that the SSL certificate presented by the client cannot be validated, preventing the establishment of a secure connection.

Below are the primary causes of this error:

1.     Expired Certificates: SSL certificates have a validity period and must be renewed periodically. If a certificate has expired, the server will not accept it, resulting in a 495 error.

2.     Untrusted Certificates: Certificates issued by a non-trusted Certificate Authority (CA) or self-signed certificates can cause this error. The server needs to trust the CA that issued the certificate.

3.     Incorrect Certificate Configuration: Misconfigured certificates, such as incorrect certificate chains or mismatched domain names, can trigger this error. The server needs an adequately configured certificate to establish a secure connection.

4.     Intermediate Certificates Missing: SSL certificate chains must include all intermediate certificates. The server will consider the certificate chain incomplete if any intermediate certificate is missing, causing a 495 error.

Understanding these causes can help diagnose and resolve the 495 SSL Certificate Error, ensuring secure and reliable connections.

Here’s how to diagnose and resolve this issue effectively.

Steps to error 495 fix:

1.     Check SSL Certificate Validity: Ensure the SSL certificate has not expired. If it is no longer valid, renew it.

2.     Verify Certificate Trust: Use a certificate from a trusted Certificate Authority (CA). Avoid self-signed certificates unless necessary for a controlled environment.

3.     Correct Certificate Configuration: Ensure the SSL certificate is configured correctly with the correct certificate chain. This includes all intermediate certificates.

Example configuration:

server {
    listen 443 ssl;
    server_name example.com;

    ssl_certificate /path/to/fullchain.pem;
    ssl_certificate_key /path/to/privkey.pem;
    # Other configurations
}

4.     Match Domain Names: Verify that the domain name on the certificate matches the server name. Mismatched domain names will cause the 495 error.

5.     Check for Intermediate Certificates: Ensure all necessary intermediate certificates are included in the certificate chain provided to Nginx.

6.     Test Configuration Changes:

• After making changes, restart Nginx to apply the new settings:

sudo systemctl restart nginx

• Use tools like openssl or SSL test websites to verify the SSL configuration is correct.

Following these steps, you can resolve the 495 error in Nginx and ensure secure, reliable connections for your users. Regular monitoring and maintenance of SSL certificates will help prevent this error in the future.

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