Running security scans has become a daily task for DevOps engineers, IT teams, and cybersecurity professionals. Most of the time, these scans are straightforward and highlight minor issues. Occasionally, a red flag appears that causes concern. One of the most common and misunderstood results is a failed TLS test or SSL certificate errors, especially when the ssl certificate installed is not properly configured.
It is easy to treat this as an urgent problem. TLS and SSL certificates are responsible for keeping communications private, encrypted, and trusted. Without them, sensitive data such as passwords, payment details, or personal information could be intercepted or modified. However, a failed TLS test is rarely a sign of an active compromise, and understanding what the error means is crucial.
More often, it indicates that your system is supporting outdated protocols, weak cipher suites, or has misconfigurations in the SSL certificate chain. Understanding exactly what the scan is reporting allows you to address the issues effectively and maintain a secure connection for your users.
This comprehensive guide explains what TLS failures mean, why they happen, and how to fix SSL certificate errors without panic.
Why SSL Certificate Errors Occur
SSL certificate errors and TLS test failures can occur for several reasons. The most common are:
Outdated TLS Versions
Older TLS versions, such as TLS 1.0 and TLS 1.1, are no longer considered secure. Security scanners and modern browsers flag them even if clients rarely use them. Supporting these outdated protocols can result in SSL protocol error messages or generic ssl protocol error notifications.
TLS 1.2 is now the minimum standard for secure communication. TLS 1.3 provides additional security and improved performance. If a scan reports support for TLS 1.0 or TLS 1.1, it usually means that the server has not explicitly disabled these protocols. Many modern browsers will refuse to connect with them. Their presence can still affect SSL certificate not trusted errors.
Weak Cipher Suites
Cipher suites are the algorithms that TLS and SSL use to encrypt communications. Older ciphers such as RC4 or MD5 are considered weak and vulnerable. If your server still lists them as supported, scanners will flag this as a vulnerability.
Common messages include:
SSL routines: ssl_choose_client_version: unsupported protocol
SSL handshake failure
SSL connection error
Weak cipher suites can also cause a mismatch error, contributing to an ssl connection error if the server and client cannot agree on an encryption algorithm during the SSL handshake.
Common SSL Certificate Errors
Certificate-related problems are one of the most frequent causes of SSL certificate errors, including expired SSL certificates that trigger error messages, self-signed certificates that result in not trusted errors, domain mismatch errors when the certificate does not match the requested website, revoked certificates that have been compromised, missing intermediate certificates in the chain, and issues with the overall certificate chain.
When a certificate is expired, not installed correctly, or issued by an untrusted certificate authority, users may see a particular error message in their browsers. Examples include messages like "Your connection is not private" or "Website's SSL certificate is not trusted."
Intermediate Infrastructure Issues
Even if the application server is properly configured, traffic may pass through a load balancer, content delivery network, or proxy that allows older protocols or weak ciphers. In these cases, SSL/TLS tests may report outdated versions despite your web server being secure. Tracing the full request path is necessary to identify where the insecure configuration exists, which may involve examining the root certificate.
Understanding SSL Errors and Certificate Status
How SSL Certificate Error Occurs
An SSL certificate error occurs when there's a mismatch between what's expected and what's presented during the SSL handshake process, which could be due to certificate status issues such as expired, revoked, or invalid certificates, a name mismatch when the certificate does not cover the domain, missing intermediate certificates in the chain, or problems with the private key not matching the server certificates.
Browser Security Certificate Handling
Modern browsers handle security certificate validation strictly. When your security certificate expires or has other issues, browsers will display warnings that can prevent users from accessing your site. The padlock icon may disappear or show as not secure, affecting user trust and website credibility.
Browser Behavior and SSL Errors
How Modern Browsers Handle SSL Certificate Issues
Modern browsers such as Chrome, Firefox, Safari, and Edge display prominent warnings when encountering SSL certificate errors. These warnings often prevent users from proceeding to the website. Common examples include:
NET::ERR_CERT_DATE_INVALID for expired SSL certificate situations
NET::ERR_CERT_AUTHORITY_INVALID for self signed certificates or untrusted authority issues
NET::ERR_CERT_COMMON_NAME_INVALID for name mismatch errors
The absence of a padlock icon or presence of security warnings in the address bar can discourage users from trusting your site. Addressing these warnings quickly is essential for maintaining security and user confidence.
Understanding Browser Security Certificate Validation
Browsers perform multiple checks during certificate validation:
Certificate status verification
Chain certificates validation
Revocation status checking
Domain name matching
Certificate's validity period verification
When any check fails, the browser may display a "not trusted error" or prevent access entirely.
How to Fix SSL Certificate Errors
To address TLS and SSL errors effectively, configure your web servers to allow only secure protocols and strong cipher suites.
Example Web Server Configurations
Nginx Configuration:
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers HIGH:!aNULL:!MD5:!RC4;
ssl_prefer_server_ciphers on;
Apache Configuration:
SSLProtocol TLSv1.2 TLSv1.3
SSLCipherSuite HIGH:!aNULL:!MD5:!RC4
SSLHonorCipherOrder on
Restart your web server after updating the configuration and re-run the SSL/TLS test using Cyber Chief. Most SSL errors should disappear.
Certificate Chain Management
Ensure your certificate chain is complete. This includes:
Root certificate from the trusted certificate authority
Any intermediate certificates in the proper order
Your server certificate with matching private key
Missing intermediate certificates often trigger SSL certificate errors and certificate not trusted error messages in browsers. Always verify that your installed SSL certificate includes the complete chain certificates.
Fixing Specific SSL Certificate Issues
Expired SSL Certificate Error
When dealing with an expired SSL certificate, you need to:
Obtain a new SSL certificate from your certificate authority
Generate a new certificate signing request if required
Install the new SSL certificate on your web server
Update the certificate's validity period in your monitoring systems
Test the secure connection to ensure the expired certificates are replaced
SSL Certificate Not Trusted Errors
These not trusted errors typically occur when self-signed certificates are used instead of certificates from a trusted certificate authority, when intermediate certificates are missing from the chain, when the certificate authority is not recognized by the client’s browser, or when the certificate revocation status cannot be verified.
Mismatch Error Resolution
A mismatch error happens when the SSL certificate does not match the domain being accessed, and solutions include installing a wildcard SSL certificate to cover multiple subdomains, using a SAN certificate (Subject Alternative Name) for multiple domains, ensuring the certificate covers all domains served by the server, and checking that Server Name Indication (SNI) is properly configured.
SSL Handshake Troubleshooting
The SSL handshake occurs when a client and server establish a secure connection, and handshake failures often indicate a TLS protocol version mismatch, unsupported cipher suites, certificate trust problems, expired or revoked certificates, or issues with client certificates when mutual authentication is required.
Common error messages include SSL handshake failure, SSL protocol error, or SSL connection error. Properly configuring TLS protocols and updating your SSL certificate typically resolves these problems.
Advanced SSL Certificate Management
SSL TLS Certificate Monitoring
Effective SSL/TLS certificate management requires tracking expiration dates to prevent expired certificate scenarios, monitoring certificate status for revocation, ensuring the private key remains secure and matches the certificate, performing regular SSL chain validation, and setting up automated alerts before the certificate expires.
Addressing Mixed Content Errors
Mixed content error occurs when secure HTTPS pages load insecure HTTP resources, which can compromise the secure connection and trigger security warnings. To fix SSL certificate-related mixed content, ensure all resources load over HTTPS, update absolute URLs in the content, use protocol-relative URLs where appropriate, and configure the web server to redirect HTTP to HTTPS.
SSL Port and Connection Configuration
Proper SSL port configuration is essential for secure connections, and standard practices include using port 443 for HTTPS traffic, configuring appropriate SSL connection timeouts, ensuring the web server handles SSL connections efficiently, and implementing proper SSL/TLS certificate rotation procedures.
SSL Certificate Installation Best Practices
Installing SSL Certificates Correctly
When you install a new SSL certificate:
Generate a new certificate signing request with proper details
Obtain the SSL certificate from a trusted certificate authority
Install the SSL certificate with all intermediate certificates
Verify the private key matches the certificate
Test the SSL connection across different browsers and devices
Check that certificates cover all required domains
Wildcard SSL Certificate Considerations
A wildcard SSL certificate can secure multiple subdomains with a single certificate, offering benefits such as simplified certificate management, cost-effectiveness for covering multiple subdomains, reduced certificate renewal overhead, and consistent security across all subdomains.
However, wildcard certificates require careful private key protection since compromise affects all covered subdomains.
Digital Certificates and Transport Layer Security
Digital certificates form the foundation of transport layer security (TLS) as they authenticate server identity, enable encrypted connections, provide secure sockets layer protection, support modern TLS protocol versions, and integrate with certificate authority validation systems.
Comprehensive SSL Certificate Troubleshooting
Step-by-Step SSL Issue Resolution
When faced with SSL errors, follow this structured process:
Check Protocol Support
Run a Cyber Chief scan to confirm which TLS versions are enabled
Disable TLS 1.0 and TLS 1.1 if present
Ensure modern TLS protocol support
Verify Cipher Suites
Ensure weak ciphers such as RC4 and MD5 are disabled
Allow only strong ciphers following current best practices
Test cipher suite compatibility
Examine SSL Certificates
Confirm that the SSL certificate has not expired
Ensure the certificate chain includes all intermediate certificates
Check if the certificate has been revoked
Verify certificate covers the correct domains
Inspect Infrastructure Layers
Examine load balancers, CDNs, and proxies
Verify they don't allow outdated protocols
Check for proper SSL port configuration
Test SSL Handshake Manually
Use Cyber Chief for comprehensive SSL validation
Look for mismatch errors or unsupported cipher issues
Verify client certificates if required
Check Browser Behavior
Test the website across multiple browsers
Look for expired certificate errors or not trusted errors
Verify the padlock icon displays correctly
Advanced SSL Certificate Scenarios
Multi-Domain and SAN Certificates
For complex hosting environments requiring SSL/TLS configuration, SAN certificates can cover multiple specific domains, wildcard certificates can handle unlimited subdomains, multi-domain certificates balance flexibility and cost, and certificate planning should take future domain needs into account.
Dedicated IP Address Considerations
While Server Name Indication (SNI) has largely eliminated the need for dedicated IP addresses for SSL, some scenarios still benefit from them, including legacy client support requirements, specific compliance requirements, high-traffic environments with performance concerns, and simplified certificate management in certain configurations.
Conclusion: Maintaining Secure SSL Connections
SSL certificates and TLS configurations are critical for maintaining secure connections and user trust. While encountering SSL certificate errors may initially seem alarming, they represent opportunities to strengthen your security posture rather than immediate crises.
By systematically addressing protocol configurations, cipher suites, certificate validity, and infrastructure layers, you can ensure your website maintains user trust and provides secure connections. Regular monitoring, proactive certificate management, and staying current with security best practices will help prevent most SSL errors before they impact users.
How? Cyber Chief helps you identify SSL certificate vulnerabilities, map TLS configurations, and implement secure certificate practices in minutes, not days.
Watch the Cyber Chief on-demand demo to see how.
Cyber Chief is built to integrate seamlessly into development workflows and offers:
Automated SSL certificate scanning identifies vulnerabilities across certificate chains, cipher suites, protocol versions, certificate expiration, and more, including alignment with current security standards.
Detailed certificate analysis highlights areas where SSL configurations are weak, outdated protocols are enabled, or certificate chains are incomplete.
Risk-based prioritization helps you understand which SSL certificate issues pose the greatest threat to your users and data security.
Actionable remediation guidance provides step-by-step recommendations, including configuration examples, for implementing secure SSL certificate practices.
Expert support on demand gives you access to security coaching to implement robust SSL/TLS configurations efficiently, reducing certificate-related risks across your infrastructure.
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