7 Common SSL Certificate Problems and How to Fix Them

An SSL certificate is an essential part of modern website security. It helps protect information exchanged between a website and its visitors by enabling encrypted HTTPS connections. It also helps visitors recognize that they are accessing a website through a secure connection. However, SSL certificate problems can undermine these benefits — causing browser warnings, broken HTTPS connections and a loss of visitor trust if left unresolved.

However, installing an SSL certificate does not always mean everything will work perfectly. Website owners can encounter SSL errors, certificate warnings, HTTPS configuration problems, mixed content issues and certificate expiration.

These problems can prevent visitors from accessing your website or cause browsers to display security warnings. The good news is that most SSL certificate problems can be identified and fixed with the right approach. In this guide, we’ll look at 7 common SSL certificate errors, why they happen and what you can do to fix them.

What Is an SSL Certificate?

An SSL certificate is a digital certificate that helps establish an encrypted connection between a website and a visitor’s browser.

When SSL is correctly installed, your website uses HTTPS instead of HTTP.

For example:

• http://yourwebsite.com

becomes:

• https://yourwebsite.com

Modern SSL certificates use encryption technologies based on TLS, which is why you may also hear the term TLS certificate.

An SSL certificate can help protect sensitive information such as login credentials, contact information and payment-related data while it travels between the user’s browser and the website.

Let’s look at some of the most common SSL issues website owners encounter.

1. SSL Certificate Has Expired

One of the most common SSL certificate problems is an expired certificate.

SSL certificates are issued for a limited period. If the certificate expires and isn’t renewed, browsers can display security warnings to visitors.

A visitor may see messages such as:

• “Your connection is not private”
• “Your connection is not secure”
• “NET::ERR_CERT_DATE_INVALID”
• “Certificate expired”

How to Fix an Expired SSL Certificate?

First, check the certificate’s expiration date.

If it has expired, renew or replace the certificate through your SSL certificate provider or hosting provider.

After renewal, make sure the new certificate is correctly installed on your server.

You should also consider enabling automatic certificate renewal where supported. Automated renewal can reduce the risk of your website unexpectedly losing HTTPS protection.

2. SSL Certificate Is Not Trusted

Another common problem occurs when a browser cannot establish trust in your SSL certificate.

This can happen when the certificate was issued by an untrusted certificate authority, was incorrectly installed or the certificate chain is incomplete.

Browsers rely on trusted Certificate Authorities (CAs) to verify website certificates.

If the browser cannot establish the required chain of trust, visitors may receive an SSL security warning.

How to Fix It?

Check that your SSL certificate was issued by a trusted Certificate Authority.

Then verify that the complete certificate chain, including the required intermediate certificate, is correctly installed on your server.

If you’re unsure about the installation, contact your hosting provider or SSL provider for assistance.

A correctly configured certificate should allow supported browsers to validate the website’s identity without displaying unnecessary warnings.

3. Mixed Content Errors

A website may have a valid SSL certificate but still display security warnings because of mixed content.

Mixed content occurs when an HTTPS website loads some resources through HTTP.

For example, your main page may load through:

• https://yourwebsite.com

but an image, stylesheet, JavaScript file or other resource may still be loaded through:

• http://yourwebsite.com/image.jpg

This creates an inconsistent security configuration.

How to Fix Mixed Content?

First, identify which resources are still being loaded over HTTP.

Common causes include:

• Images
• CSS files
• JavaScript files
• Fonts
• Videos
• External resources
• Plugin-generated URLs

Update those URLs from HTTP to HTTPS.

If you’re using WordPress, check your website URL settings and update plugins, themes and database references that still use HTTP.

A proper HTTPS website configuration should ensure that important resources are loaded securely.

4. SSL Certificate Does Not Match the Domain

An SSL certificate is issued for specific domain names.

If the certificate installed on your server doesn’t include the domain visitors are accessing, the browser may display a certificate name mismatch error.

For example, a certificate may be configured for:

• www.example.com

while visitors are accessing:

• example.com

If both versions aren’t properly covered by the certificate, you may encounter an SSL hostname mismatch.

How to Fix a Certificate Name Mismatch

Check the domain names listed on your SSL certificate.

Make sure the certificate covers all versions of your website that visitors are expected to use.

Depending on your setup, this may include:

• example.com
• www.example.com
• Relevant subdomains

A Wildcard SSL certificate can be useful when you need to secure multiple subdomains under the same domain.

After installing the correct certificate, verify that your HTTP-to-HTTPS redirects and DNS settings are also configured correctly.

5. SSL Certificate is Not Installed Correctly

Sometimes an SSL certificate is valid but isn’t correctly configured on the web server.

This can happen when:

• The wrong certificate file is installed
• The private key doesn’t match
• Intermediate certificates are missing
• The certificate is installed on the wrong server
• Server configuration is incorrect
• A hosting migration was completed without reinstalling SSL

As a result, visitors may receive SSL connection errors.

How to Fix Incorrect SSL Installation?

Start by checking your server’s SSL configuration.

Confirm that:

• The correct certificate is installed.
• The private key matches the certificate.
• Required intermediate certificates are installed.
• The certificate is installed on the correct server.
• The server is configured to serve HTTPS traffic.

If you recently moved your website to a new hosting provider, verify that the SSL certificate has been installed on the new server.

For website owners who aren’t comfortable with server configuration, asking your hosting provider to check the SSL installation can save time and prevent configuration mistakes.

6. HTTPS Redirect is Not Working

Installing an SSL certificate is only part of moving a website from HTTP to HTTPS.

You also need to ensure that visitors are properly redirected from the HTTP version to the HTTPS version.

For example:

• http://example.com

should redirect to:

• https://example.com

Without a proper HTTP to HTTPS redirect, visitors may continue accessing the unsecured version of your website.

Incorrect redirects can also create redirect loops or cause pages to become inaccessible.

How to Fix HTTPS Redirect Problems?

Check your website’s redirect configuration.

Depending on your hosting environment, redirects may be managed through:

• Web server configuration
• .htaccess
• Hosting control panel
• WordPress settings
• CDN configuration
• Security or caching plugins

Make sure there is one clear redirect path from HTTP to HTTPS.

After making changes, test both the www and non-www versions of your domain.

7. SSL Certificate Has Been Installed but the Website Still Shows “Not Secure”

One of the most confusing situations is when an SSL certificate appears to be installed correctly, but the browser still displays a “Not Secure” warning.

There can be several reasons for this.

The website might still contain HTTP resources, the certificate may not cover the correct domain, redirects may be incorrect or the browser may be displaying a cached version of the site.

How to Fix a “Not Secure” Website?

Start by checking the SSL certificate and confirming that it is valid for your domain.

Then:

• Check for mixed content.
• Confirm HTTPS is enabled.
• Check HTTP-to-HTTPS redirects.
• Verify the certificate hasn’t expired.
• Clear website and browser caches.
• Check your WordPress site URL settings if applicable.
• Review CDN and proxy settings.
• Test the website across different browsers.

If the problem persists, use an SSL testing tool to identify certificate chain, hostname or configuration problems.

Final Thoughts

SSL certificate problems can be frustrating, particularly when they prevent customers from accessing your website or display alarming security warnings.

The most common issues include expired SSL certificates, certificate trust problems, mixed content, domain mismatches, incorrect SSL installation, HTTPS redirect errors and “Not Secure” warnings.

The key is to identify the specific cause rather than simply reinstalling the certificate repeatedly.

Regular SSL monitoring, proper HTTPS configuration, timely certificate renewal and good website maintenance can help prevent many common problems.

If your website relies on HTTPS, don’t treat SSL as a one-time installation. Make it part of your ongoing website security and maintenance strategy.

A valid and correctly configured SSL certificate helps create a safer browsing environment for visitors and provides an important foundation for a secure, professional website.