How to Fix the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT Error

Dealing with the error code: mozilla_pkix_error_self_signed_cert can be frustrating, but don’t worry—there are several ways to resolve it and ensure smooth, secure browsing. Whether you’re a website owner or just visiting, understanding how to fix the “mozilla_pkix_error_self_signed_cert error” is essential.

This guide will walk you through obtaining a trusted SSL certificate, adjusting Firefox settings, and tweaking your antivirus software. Follow these steps to keep your online activities safe and seamless. Let’s dive into the solutions and get your browsing back on track!

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What is the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT Error?

The “MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT” error in Firefox occurs when the website you’re trying to visit uses a self-signed SSL/TLS certificate. These certificates are not trusted by browsers because they are not issued by a recognized Certificate Authority (CA). As a result, Firefox and other browsers will block access to such sites, showing a security warning.

As a website owner, you need to understand why a trusted authority doesn’t validate your certificate. As a visitor, you should be cautious as this could imply potential security risks.

For Website Owners

If you’re the owner of the website, you should replace the self-signed certificate with one from a trusted CA. These certificates are affordable and provide security assurance to your visitors. Prices start as low as $7 per year, and many come with generous SSL warranties up to $1,500,000.

For Website Visitors

If you’re a visitor encountering this error, you can try the following methods to bypass it. Follow these steps one by one until the issue is resolved.

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How to Fix the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT Error

To address the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT error, you can take several approaches.

You might bypass the warning temporarily, add the site to Trusted Sites in Windows, or adjust your antivirus and firewall settings.

Additionally, clearing your SSL state and browsing data can resolve the issue.

Bypass the Warning

You can bypass the warning and proceed to the website, though this is not recommended for sites that handle sensitive information.

1. Click on Advanced.
2. Click on Accept the Risk and Continue.
   
   

If this method doesn’t work, you can manually add the self-signed certificate to your browser’s trusted certificate store. However, please be aware that bypassing such warnings can pose security risks, as it might allow malicious certificates to be trusted.

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Add the Site to Trusted Sites (Windows)

1. First, open the Control Panel and navigate to ‘Internet Options.’
2. Go to the Security tab and select ‘Trusted Sites.’ Click on the ‘Sites‘ button, which will open a new window. Here, you can add the website URL. Make sure the URL starts with ‘https://’ and then click ‘Add.’ If necessary, uncheck the box labeled ‘Require server verification (https:) for all sites in this zone.’
   
   
3. After that, click ‘Close‘ and then ‘OK‘ to save your changes. This action instructs Windows to trust the certificate from the specified site, which will bypass the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT error in Firefox. However, be cautious when adding sites to the Trusted Sites list, as it can expose your system to risks if the site isn’t secure.

Once you’ve added the site, restart Firefox and try accessing the site again. If the error persists, you may need to restart your computer to fully apply these settings. This method is useful for internal or development sites where self-signed certificates are common. Always make sure you trust the site completely before proceeding with this solution.

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Add the Site to Trusted Sites (Mac)

For Mac users, follow these steps to trust a self-signed certificate:

1. Open Keychain Access. You can find it in the Applications > Utilities folder or by searching for it using Spotlight.
2. In the Keychain Access window, select the ‘System‘ keychain from the list on the left.
3. Click the lock icon at the top of the window to unlock it. You may need to enter your administrator password.
   
   
4. From the menu bar, select File > Import Items.
5. Locate and select the self-signed certificate file you want to trust, then click ‘Open.’
6. Find the imported certificate in the list. It may be listed under the name of the issuing authority.
7. Double-click the certificate to open its information window.
8. Expand the ‘Trust‘ section by clicking the small arrow next to it.
9. Change the ‘When using this certificate‘ option to ‘Always Trust.’
   
   
10. Close the certificate information window. You may need to enter your administrator password again to save the changes.
11. Restart your browser and try accessing the site again.

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Adjust Antivirus and Firewall Settings

Adjusting your antivirus and firewall settings can often resolve the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT error by ensuring that these security tools aren’t interfering with the website’s certificate.

Start by checking your antivirus software for any SSL or HTTPS scanning settings. While designed to protect you, these features can sometimes misinterpret legitimate certificates as threats. Disable SSL or HTTPS scanning temporarily and reload the webpage to see if the error persists.

Next, review your firewall settings. Firewalls can block certain certificates if they’re self-signed. Open your firewall settings and look for SSL or certificate filtering options. Disable these settings if present. If you use a corporate network, consult your IT department as they may have specific security protocols.

Additionally, some antivirus programs install their own certificates, which can conflict with Firefox’s security protocols. Consider temporarily turning off your antivirus software to test if it’s causing the issue. Remember to re-enable it afterward to maintain your security.

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Clear SSL State

To clear the SSL state in Windows:

1. Open the Control Panel.
2. Navigate to ‘Internet Options.’
3. Go to the ‘Content‘ tab.
4. Click the ‘Clear SSL state‘ button.
   
   
5. A confirmation message will appear, indicating that the SSL cache has been successfully cleared.

This process specifically targets SSL/TLS certificates, ensuring no remnants of invalid certificates interfere with your secure connections.

For macOS:

1. Open the ‘Keychain Access’ application.
2. Select ‘System Roots‘ from the sidebar.
3. Choose all entries and delete them.
   
   

After clearing the SSL state, restart your browser and revisit the site that triggered the error. This step forces a clean retrieval of the website’s SSL certificate. If the error persists, further troubleshooting steps will be necessary.

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Clear Browsing Data

Clearing your browsing history and cache can also resolve the error.

1. Open Firefox and go to Settings.
2. Select Privacy & Security.
3. Click on Clear Data under Cookies and Site Data.
   
   
4. Select Clear History and check all boxes.
5. Click Clear Now.

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Trust Root Authorities in Firefox

1. Firefox can be configured to trust root certificates in the Windows certificate store.
2. Type about:config in the address bar and press Enter.
3. Click on I accept the risk!.
   
   
4. Search for security.enterprise_roots.enabled.
5. If the value is False, double-click to set it to True.
   
   
6. Restart Firefox.

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Alternative Method (Manual Importing)

1. Open Firefox and click the menu button (three horizontal lines) in the top-right corner.
2. Select ‘Settings‘ and go to the ‘Privacy & Security’ tab.
3. Scroll down to the ‘Certificates‘ section and click on ‘View Certificates.’
   
   
4. In the Certificate Manager window, switch to the ‘Authorities‘ tab.
   
   
5. Click the ‘Import’ button and navigate to the location of the root certificate file on your system.
6. Select the root certificate file. Firefox will prompt you to choose the trust settings for this certificate.
7. Check the box that says, ‘Trust this CA to identify websites,’ and click ‘OK.’
8. Restart Firefox to apply the changes.

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Update Security Settings via the Command Prompt

Updating certain security settings might resolve the error.

1. Open Command Prompt as an administrator.
2. Enter the following commands one by one, pressing Enter after each:
   
   Regsvr32 softpub.dll
   Regsvr32 Wintrust.dll
   Regsvr32 Wintrust.dll
   
   
3. Restart your computer.

Regsvr32 softpub.dll: Registers the DLL (Dynamic Link Library) responsible for handling digital certificates.
Regsvr32 Wintrust.dll: Registers the DLL that verifies the trustworthiness of files and certificates.

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Conclusion

To resolve the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT issue, securing a trusted SSL certificate from a reputable CA is key. As a website visitor, you can avoid warnings by managing certificate settings or adjusting antivirus configurations. Clearing browsing data and updating security settings can also help. Learning how to fix the MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT error enhances security and user experience, making your website more reliable and accessible.