SSL Certificate Errors: How to Fix Common Issues

You know that feeling when you click on a site, and your browser slams the brakes with a scary warning? That’s an SSL certificate error. It instantly kills trust, even if the site’s legit. Whether you’re managing a personal blog or running an online store, this can cost you visitors, sales, and reputation.

The good news? Most SSL certificate errors are common and fixable. You don’t need to panic. We’ll walk through the causes, the fixes, and the tools to help you keep your site secure and visitors confident.

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Table of Contents

1. What is an SSL Certificate Error?
2. Common Types of SSL Certificate Errors and How to Fix Them
3. How to Identify and Diagnose SSL Certificate Errors
4. Best Practices for SSL Certificate Management

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What is an SSL Certificate Error?

An SSL certificate error occurs when a browser cannot verify that a website’s SSL certificate is valid or trusted. Common causes include expired certificates, domain mismatches, self-signed certificates, or untrusted issuing authorities, which prevent secure HTTPS connections and trigger browser warnings.

This check isn’t random. Browsers like Google Chrome and Firefox follow a strict validation process. They look at the SSL certificate’s expiration date, confirm a trusted certificate authority signed it, and verify the domain name matches. They also check the certificate’s revocation status using OCSP or CRL methods. If the certificate is revoked, expired, self-signed, or poorly installed, the browser blocks access and warns the user that the site isn’t safe.

There are two main categories of SSL errors: server-side and client-side. Server-side issues come from misconfigured servers, an expired SSL certificate, a self-signed certificate, or a missing certificate signing request. You might also see a mismatch error when the certificate doesn’t match the domain name. On the other hand, client-side issues can come from bad antivirus settings, old browsing data, or wrong system time.

These problems impact your business fast. Visitors will lose trust when the errors appear. They won’t stay on a site that looks unsafe. This leads to higher bounce rates and fewer conversions. A broken SSL/TLS connection also affects your SEO rankings, since search engines prefer secure sites. Worse, your brand may look careless, even if you’re not.

That’s why every SSL issue needs immediate attention. When the website’s SSL certificate works right, users stay, data stays safe, and you stay credible.

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Common Types of SSL Certificate Errors and How to Fix Them

Not all SSL connection errors are the same. Some show up because of expired certificates, others because the certificate chain isn’t correctly set up. Sometimes it’s a simple name mismatch error, and other times it’s your server missing an intermediate certificate. Each issue breaks the secure connection, damages trust, and needs a specific fix. Let’s break down the most common error types.

1. Expired Certificate Errors

An expired SSL certificate error occurs when the certificate has passed its expiration date. Every SSL certificate has a set validity period of one year. When it ends, the certificate authority no longer considers it valid.

Most browsers immediately block access and display warnings like “Your connection is not private” or “The site’s security certificate has expired.”

In Google Chrome, you’ll see a warning with the label “NET::ERR_CERT_DATE_INVALID.” On Firefox, it reads “SEC_ERROR_EXPIRED_CERTIFICATE.” Safari shows a similar warning, alerting users to a failed secure connection. These warnings scare visitors off instantly.

Certificates expire to keep the SSL/TLS certificate system secure. A short validity period limits the risk if a private key gets compromised. But when you let your certificate lapse, your website’s server loses all credibility. Users bounce. Some never come back.

Here’s how to fix it:

• Log in to your account where you manage your SSL certificate
• Generate a new certificate signing request (CSR) if required.
• Buy or reissue a new SSL certificate through a trusted certificate authority like Sectigo or DigiCert.
• Install the updated certificate on your web server.
• Test the setup using SSL tools to confirm it works.
• Set up auto-renewal if available.
• Use calendar reminders or monitoring tools to avoid another expired certificate issue.
• SSL Dragon can notify you before your security certificate expires, so you never miss a deadline.

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2. Name Mismatch Errors

A name mismatch error appears when the SSL certificate installed doesn’t match the domain name in the browser’s address bar. Let’s say your certificate was issued for www.example.com, but the visitor typed example.com. If the certificate doesn’t cover both, browsers show an error.

Google Chrome shows a “NET::ERR_CERT_COMMON_NAME_INVALID” message. Firefox warns with “SSL_ERROR_BAD_CERT_DOMAIN.” Safari flags the site as using an invalid certificate.

You’ll see these messages when there’s a gap between the domain name the browser expects and what the certificate covers.

Common causes include:

• Incorrect certificate signing request (CSR)
• Missing wildcard SSL certificate for subdomains
• Lack of multi-domain support
• No redirect between www and non-www versions

How to fix it:

• Buy a wildcard SSL certificate if you use subdomains like shop.example.com or blog.example.com.
• If you manage multiple domains, go for a multi-domain SSL certificate.
• Ensure the CSR includes all variations of the domain name you plan to use.
• Update DNS and server settings to redirect users between www and non-www versions.
• Confirm the certificate covers every domain and subdomain users might enter.

Keeping your SSL configurations tight and aligned with your domain setup prevents this issue entirely. SSL Dragon offers wildcard and multi-domain certificates, which handle this smoothly and cleanly.

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3. Self-Signed Certificate Errors

A self-signed certificate skips the certificate authority step. Instead of being issued by a trusted third party, it’s generated and signed by the site owner. Self-signed certs might work for testing or internal tools, but public browsers don’t trust them. That’s why browsers display warnings like “The certificate is not trusted” or “This SSL certificate was not issued by a trusted certificate authority.”

You’ll see this error when visiting development servers or internal dashboards. Chrome and Firefox both block access unless you explicitly bypass the warning. Users must click “Advanced” and manually proceed, something most won’t do.

When is this okay? Only in closed environments. Never use a self-signed certificate for a public-facing site. It destroys trust and triggers a certificate error instantly.

Here’s how to fix it:

• Choose a valid SSL certificate from a trusted certificate authority.
• Use SSL Dragon to pick the right one: a domain-validated, organization-validated, or wildcard SSL certificate, depending on your setup.
• Generate a correct certificate signing request (CSR) from your hosting dashboard or server.
• Submit the CSR and get the signed certificate.
• Upload and install it on your web server.
• Test the site and confirm that all browsers accept the SSL certificate.

SSL Dragon works with GeoTrust, GoGetSSL, and Thawte, giving you verified options instead of sketchy self-signed certificates. It’s safer and protects your site from trust-killing warnings.

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4. Mixed Content Errors

A mixed content error pops up when a secure HTTPS page tries to load some elements (like images, scripts, or CSS) over HTTP. This breaks the SSL/TLS protection and triggers warnings in all major browsers.

The problem usually comes from outdated links or third-party widgets. Google Chrome labels these with warnings like “Your connection to this site is not fully secure.” Firefox shows a broken padlock icon, and Safari may block specific insecure content from loading.

Common culprits include:

• Hardcoded http:// links in your site’s HTML or CMS
• Embedded resources from old plugins
• External content from non-secure sources

How to fix this:

• Use browser developer tools (F12) to inspect which resources load over HTTP.
• Update all http:// links to https:// inside your code, templates, or CMS.
• Use plugins that find and fix mixed content for WordPress or similar platforms.
• Use online tools like Why No Padlock to detect remaining insecure items.
• Scan external scripts and ensure they come from sources using SSL certificates.

Mixed content breaks the secure connection, exposing your users to risk. Cleaning it up improves both security and user trust. It also helps preserve your SEO rankings by showing a fully secure site. SSL Dragon offers resources to help you get this right across different CMS platforms.

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5. Invalid Certificate Chain Errors

An invalid certificate chain error means your browser couldn’t verify the whole chain of trust between your SSL certificate and a root certificate. These chains rely on intermediate certificates, which bridge your site’s certificate and the trusted certificate authority.

The browser can’t validate the site if the web server doesn’t present the whole chain, or an intermediate certificate is missing. Chrome displays “NET::ERR_CERT_AUTHORITY_INVALID.” Firefox shows “SEC_ERROR_UNKNOWN_ISSUER.” In both cases, browsers tell users the website’s certificate isn’t trusted.

The error often happens when:

• You installed only the primary certificate, not the complete CA bundle
• Your server lacks proper SSL configurations
• You didn’t upload the intermediate certificates in the correct order

Here’s how to fix it:

• Download the complete certificate bundle (including intermediates) from your CA.
• Upload and install all parts of the chain on your website’s server.
• Confirm your SSL certificate installed matches the correct order: server certificate → intermediates → root.
• Use tools like SSL Labs to validate the setup.

A properly formed chain builds user trust and ensures browsers connect without any SSL protocol error.

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6. Certificate Revocation Errors

A certificate revocation error shows up when a browser checks the revoked certificates list and finds your SSL certificate there. It happens when the certificate authority cancels a certificate before it expires, usually because the private key was compromised or issued incorrectly.

Browsers use two main methods to check revocation: CRLs (Certificate Revocation Lists) and OCSP (Online Certificate Status Protocol). Chrome and Firefox check this in the background during the SSL handshake. If the certificate is on the revoked list, users see errors like “The certificate has been revoked” or “Revocation status could not be verified.”

Reasons for revocation include:

• Lost or exposed private key
• Compromised web server
• Malicious activity or fraud
• CA-issued replacement certs

Here’s how to fix it:

• Generate a new certificate signing request
• Contact your CA or SSL Dragon to get a new SSL certificate
• Reinstall the new certificate on your server
• Enable OCSP stapling for better performance
• Remove the revoked cert completely

To prevent this, protect your private key, limit server access, and monitor for suspicious changes. If a revocation ever happens, treat it like an emergency. SSL Dragon can help with fast issuance and cleanup. The longer your website’s SSL certificate is compromised, the more users you’ll lose.

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7. Client-Side SSL Errors

Sometimes, an SSL certificate error occurs not because of a misconfigured server but because something is wrong on the visitor’s side. These client-side SSL errors are common and can block access even if the site uses a valid SSL certificate from a trusted CA.

The most frequent causes include incorrect system time and date, outdated browsing data, or aggressive antivirus settings that interfere with the SSL handshake. A user might also have browser extensions or firewalls that block parts of the certificate chain, causing a secure connection to fail.

Here’s what users can do to fix it:

• Clear browser cache and cookies
• Make sure the computer’s date and time are correct
• Disable HTTPS scanning in antivirus software
• Try accessing the site in a different browser
• Update to the latest browser version
• Restart the device and router

These steps resolve many SSL connection errors on the client side. If the SSL certificate passes all the SSL test scans, the issue likely comes from the user’s local setup.

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How to Identify and Diagnose SSL Certificate Errors

Before fixing an SSL certificate error, you must identify exactly what’s wrong. Browsers display error messages differently, but all warn users when a secure connection fails due to SSL issues.

In Google Chrome, you might see:

• NET::ERR_CERT_COMMON_NAME_INVALID
• ERR_CERT_AUTHORITY_INVALID
• ERR_CERT_DATE_INVALID.

These point to mismatch errors, an expired SSL certificate, or an untrusted certificate authority. Chrome also marks the site as “Not Secure” in the address bar.

Mozilla Firefox shows errors like:

• SEC_ERROR_UNKNOWN_ISSUER 
• SSL_ERROR_BAD_CERT_DOMAIN.

These often come from a self-signed certificate or a broken certificate chain. Firefox highlights broken TLS protocol connections with full-screen alerts.

In Safari, you’ll get messages like “This connection is not private,” indicating an SSL certificate problem or an issue with the website’s certificate. Similar alerts appear on mobile but are less detailed.

To dig deeper, open browser developer tools (F12). Navigate to the “Security” tab to check the certificate chain, expiration date, and whether the SSL certificate is properly configured. You can also inspect the root domain, intermediate certificates, and certificate authority.

Online tools also help. Run your domain through:

• SSL Labs server test
• SSL Checker
• Why No Padlock

These tools flag common SSL errors, confirm if the SSL certificate is valid, and test for missing root certificates or outdated encryption. Together, they give you a clear view of what needs fixing.

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Best Practices for SSL Certificate Management

Here’s how to prevent SSL errors with fully configured SSL certificates that build trust and keep your site safe.

• Choose the Right SSL Certificate: Pick a certificate based on your website structure. A wildcard SSL certificate secures all subdomains under a single domain, while multi-domain certificates cover multiple domains. For a single site, a basic domain-validated SSL certificate works. Matching the right type avoids mismatch errors and prevents confusion during the certificate signing request process.
• Set Up Certificate Monitoring and Alerts: Monitor expiration dates. Use automated tools or services that alert you when your security certificate expires or becomes invalid. This prevents expired certificates from disrupting your website and protects it from being flagged with a warning during peak traffic.
• Document Renewal Tasks Clearly: Know who’s responsible for renewing each certificate and when. Keep a schedule and assign clear roles within your team. Whether you’re managing one SSL certificate or dozens, documented steps avoid confusion and lower the risk of forgotten renewals or improperly installed SSL certificates.
• Test After Every Installation: After you install a new SSL certificate, run diagnostics. Use tools like SSL Labs or SSL Checker to verify all the parameters. Testing avoids silent failures that only show up as broken connections or blocked pages for your visitors.
• Keep Server Software Updated: TLS protocols change. Update your server and OS regularly to avoid outdated encryption algorithm issues or failed SSL handshakes. This ensures full support for modern SSL/TLS certificates and better protection against attacks targeting weak SSL configurations or legacy cipher suites.
• Manage Certificates Across All Domains: If you run multiple websites, track all certificates in one place. A certificate inventory helps you stay organized, especially when working with different certificate authorities or expiration dates. Losing track leads to common SSL certificate errors.
• Automate Where Possible: If you’re using Let’s Encrypt, set up automatic renewals. For premium certificates, automation suites, calendar reminders, and email alerts work well. Automation reduces human error and protects against unexpected SSL certificate problem alerts.
• Use SSL Dragon’s Management Tools: SSL Dragon offers tools that simplify everything, from generating a certificate signing request to tracking renewals and getting help with SSL chain issues. With support for trusted certificate authorities and premium options, you get control without needing to troubleshoot every SSL issue manually.

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Stop SSL Errors Before They Start

If you’re dealing with SSL certificate errors or want a secure setup from the start, SSL Dragon has what you need. Choose from trusted brands, including wildcard SSL certificates, multi-domain options, and more. Every certificate comes with clear instructions and expert-verified reliability.

With competitive pricing and responsive customer service, SSL Dragon makes it easy to get the proper certificate for your website. Whether you’re securing one domain or many, you’ll find what fits, no upsells, no confusion. Browse the full range today and get peace of mind with a valid SSL certificate you can count on.