How to fix “ERR_SSL_UNSUPPORTED_CERTIFICATE”. Free immediate support

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How to fix “ERR_SSL_UNSUPPORTED_CERTIFICATE”. Free immediate support






How to Fix the ERR_SSL_UNSUPPORTED_CERTIFICATE Error

Learn how to troubleshoot the ERR_SSL_UNSUPPORTED_CERTIFICATE error caused by invalid, expired, or misconfigured SSL certificates. This guide covers common causes, such as unsupported encryption algorithms and domain mismatches, and provides simple steps to verify certificates, update server configurations, and resolve SSL issues effectively.

Use our free chatbot to get guided help with resolving technical problems like this.

Key Takeaways

  • ERR_SSL_UNSUPPORTED_CERTIFICATE occurs when an SSL certificate presented by your server is invalid, improperly configured, or unsupported by the connecting client.
  • Common causes include expired certificates, unsupported encryption algorithms, or certificate misconfigurations.
  • This guide provides step-by-step solutions to troubleshoot the issue, helping users verify SSL certificates, correct server configurations, and maintain optimal security.

Step-by-Step Guide to Fix the ERR_SSL_UNSUPPORTED_CERTIFICATE Error

1. Understand the ERR_SSL_UNSUPPORTED_CERTIFICATE Error

This error often occurs when the certificate provided by your web server is incompatible with the browser or client. It can stem from several causes, such as:

  • Expired or self-signed certificates.
  • Mismatched domain names in the certificate.
  • Outdated encryption methods or protocols.

2. Check the Certificate's Validity

Ensure your SSL certificate is valid and correctly configured:

  1. Visit SSL Labs' SSL Test to analyze your site's SSL implementation.

  2. Look for common certificate errors such as:

    • Expiration Date: The certificate might have expired.
    • Domain Mismatch: The certificate is not issued for your domain.
    • Incomplete Chain: Missing intermediate certificates.

    By comparing your findings, you can narrow down the exact issue.

3. Renew an Expired or Self-Signed Certificate

If the SSL certificate has expired or is self-signed:

  • Reach out to your Certificate Authority (e.g., Let’s Encrypt or DigiCert) to renew the certificate.
  • Replace auto-generated self-signed certificates with one from a trusted authority.

Here’s how you can generate a Let's Encrypt SSL certificate via Certbot:

sudo apt-get update
sudo apt-get install certbot
sudo certbot --apache

For Windows users, consider third-party tools like EaseUS LockMyFile to enhance security for encryption needs. You can find it here.

Affiliate Recommendation: If you want a simple and secure VPN to protect your online operations, check out NordVPN. A good VPN ensures encrypted communication regardless of your SSL configuration.

4. Verify Domain Name (Subject Alternative Name – SAN)

Be sure your certificate includes the right domain(s). SSL certificates must include the exact name of the domain served.

  1. Find the certificate settings in your web server configuration files (e.g., Apache's ssl.conf or NGINX's default.conf).
  2. Ensure all your subdomains are listed under Subject Alternative Name (SAN):
    • example.com
    • www.example.com

For instance:

openssl x509 -in your_cert.pem -text -noout

Tip: Use wildcard SSL certificates when managing multiple subdomains.

5. Update Your Web Server Configuration

Outdated server configurations can cause certificate errors. Update your server settings as follows:

Apache (HTTPS Configuration)

  1. Locate your Apache config file:

    /etc/httpd/conf.d/ssl.conf

  2. Confirm the file includes the correct certificate paths:

    SSLCertificateFile /etc/ssl/certs/example.crt
SSLCertificateKeyFile /etc/ssl/private/example.key
SSLCertificateChainFile /etc/ssl/certs/chain.crt

  3. Restart Apache:

    sudo systemctl restart apache2

NGINX (HTTPS Configuration)

  1. Open your NGINX default.conf file: 
    nano /etc/nginx/sites-available/default
  2. Ensure it refers to the SSL certificate and key: 
    listen 443 ssl;
ssl_certificate /etc/ssl/certs/example.crt;
ssl_certificate_key /etc/ssl/private/example.key;
  3. Test and reload NGINX: 
    nginx -t
sudo systemctl reload nginx

6. Ensure Supported SSL/TLS Versions

Older versions of SSL/TLS protocols (e.g., SSL 3.0, TLS 1.0) are unsupported by many modern browsers.

Enable TLS 1.2/1.3:

  1. In your config, ensure only secure TLS protocols are enabled:

    ssl_protocols TLSv1.2 TLSv1.3;

  2. Restart your web server to apply changes.

Pro Tip: Use Qualys SSL Labs to ensure your server is compliant with updated protocols.

7. Fix Intermediate Certificate Chain Issues

If your browser reports an "incomplete certificate chain":

  1. Download the missing Intermediate Certificate from your SSL provider.
  2. Append it to your certificate file. For example: 
    cat intermediate.crt >> example.crt
  3. Update your server configuration and restart.

8. Debug Using Browser Tools

Modern browsers provide tools to analyze SSL errors. Here’s how:

  • Chrome:

    1. Visit your website, click the lock icon in the address bar.
    2. Open Certificate (Valid) to view details.
    3. Click Details to identify specific errors.

  • Firefox:

    1. Visit your site, click the lock symbol > More Information > View Certificate.

Pro Tip: If you're frequently switching environments, tools like EaseUS OS2Go can carry your server's configuration across platforms. Learn More Here.

9. Seek Expert Help

Still facing issues? Try forums like Stack Overflow or Discord communities focused on web hosting and HTTPS configurations.

For a security-first approach, consider outsourcing critical SSL configurations to services like NordPass. Learn More Here.

Frequently Asked Questions (FAQ)

1. Why do I get the ERR_SSL_UNSUPPORTED_CERTIFICATE error?

This error typically occurs when your SSL certificate is either invalid, out-of-date, or improperly configured.

2. How can I test my website's SSL certificate?

Use tools like SSL Labs or online services provided by your Certificate Authority.

3. What happens if I don’t renew my SSL certificate?

Browsers will mark the website as insecure, and most modern browsers block access for visitors.

4. Can expired certificates be temporarily bypassed?

You shouldn't bypass expired certificates. Instead, renew the certificate immediately. For development purposes, locally trust the self-signed certs temporarily.

5. What tools can I use to automate SSL renewal?

Let’s Encrypt with Certbot is a free, automated, and trusted solution.

6. Are SSL errors browser-specific?

Yes, some browsers implement stricter policies on SSL than others.

By following this guide and the steps above, you should be able to eliminate the ERR_SSL_UNSUPPORTED_CERTIFICATE error efficiently, ensuring users enjoy a secure browsing experience on your website.

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