Fixed SEC_ERROR_BAD_SIGNATURE bug in Firefox

The SEC_ERROR_BAD_SIGNATURE error in Firefox prevents users from accessing websites in the browser. Since this is a browser error, you may be able to access the website using other browsers. Before proceeding with the solution, you should check if the site is authentic by opening it in another trusted browser (such as Chrome or Edge) and checking it.


What causes SEC_ERROR_BAD_SIGNATURE error code in Mozilla Firefox?

What causes SEC_ERROR_BAD_SIGNATURE error code in Mozilla Firefox?

This error message does not appear on suspicious sites, but it may also prevent you from accessing sites like Facebook, etc. This problem may be caused by the following factors.

The SEC_ERROR_BAD_SIGNATURE error problem is mainly caused by third-party programs or security software installed on your computer. To solve the problem, we recommend that you disable the antivirus program on your computer and check if the web pages are properly opened.

Extensions or add-ons installed in your browser also cause various problems if they are corrupted. Sometimes, without your knowledge, certain extensions are installed on your computer and this can cause a similar problem.


How to fix SEC_ERROR_BAD_SIGNATURE error code in Mozilla Firefox?

How to fix SEC_ERROR_BAD_SIGNATURE error code in Mozilla Firefox?

Disable third-party antivirus programs

The first thing to do when you get an error message is to disable the third-party antivirus software you have on your system. In most cases, antivirus software restricts your system’s ability to connect to the Internet, preventing you from accessing certain websites. To disable the antivirus software on your system, close your browser and see if that solves the problem.

If it solves the problem, then you will need to add an exception to the network settings of your antivirus program for Firefox.

Using Mozilla Firefox in Safe Mode

Your web browser extensions can also interfere with certain connections and certificates, which can cause various problems. You should run Firefox in safe mode, which will disable all extensions and make the browser work with factory settings. If that solves your problem, you’ll have to manually uninstall the extensions until you find the culprit. Here’s how to get Firefox to work in safe mode:

  1. Start Mozilla Firefox.
  2. Click on the menu button in the upper right corner, click Help, and then click “Restart with extensions disabled.”
  3. Firefox will now start in safe mode.
Changing Network Settings

Another option is to change the network settings of your Firefox browser. If you don’t use a proxy to connect to the internet, you should disable it in Firefox. If you do, you will have to compare it with other web browsers. Here’s how to disable proxies:

  1. Open Mozilla Firefox.
  2. Click on the menu button and then on Options.
  3. Under General, scroll down to the Network Settings section.
  4. Click Settings.
  5. Select No proxy and then click OK.
  6. Close the tab to save your changes.
  7. Restart Firefox.
  8. See if this solves the problem.


Frequently Asked Questions

  1. In the Tools menu, click the Options -> Advanced tab.
  2. Click the Encryption tab.
  3. Click View Certificates.
  4. Click the Servers tab.
  5. In the Certificate Name column, find the z/OSMF CertAuth section.
  6. Select the certificate files in the z/OSMF section and click Delete.
  7. Click OK.

  1. Check the time and date.
  2. Restart your router.
  3. Check your system for malware.
  4. Clear your Firefox browser history.
  5. Temporarily turn off your antivirus program.
  6. Use private mode.

  1. Go to Firefox -> Help -> Troubleshooting Information.
  2. Click the "Reset Firefox" button.
  3. Firefox will close and restart. When it's finished, Firefox will display a window with the imported information. Click "Done."
  4. Firefox will open with all factory settings.

  1. Diagnose the problem with an online tool.
  2. Install an intermediate certificate on your web server.
  3. Create a new certificate signing request.
  4. Upgrade to a dedicated IP address.
  5. Get an SSL certificate with a wildcard.
  6. Replace all URLs with HTTPS.
  7. Update your SSL certificate.

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Mark Ginter is a tech blogger with a passion for all things gadgets and gizmos. A self-proclaimed "geek", Mark has been blogging about technology for over 15 years. His blog,, covers a wide range of topics including new product releases, industry news, and tips and tricks for getting the most out of your devices. If you're looking for someone who can keep you up-to-date with all the latest tech news and developments, then be sure to follow him over at Microsoft.