Hi, it is Kaspersky which is the issue. Please make sure it is up to date and then visit the Kaspersky Forum https://forum.kaspersky.com/ to look for information to help you.

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate.

• https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can
• https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites
• https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message
• https://support.mozilla.org/en-US/kb/connection-untrusted-error-message
• http://kb.mozillazine.org/Error_loading_websites

Please let us know if this solved your issue or if need further assistance.

As you know, Kaspersky has a feature to intercept your browsing to filter it. For secure sites, this requires presenting fake certificates to Firefox, so naturally, Firefox raises the alarm.

This article describes where to manage that setting: How to troubleshoot security error codes on secure websites.

I believe Kaspersky can automatically set up Firefox to work with this feature, but I don't know whether you need to trigger it from its control panel or restart your system, or take some other action. You also can manually import their signing certificate as a last resort, but that's not usually necessary.

Note: If you haven't updated Kaspersky for a while, make sure you have the latest program update. Firefox changed the name of the certificate store file from cert8.db to cert9.db at some point in recent months, and older versions may not know about it.

It appears that it has resolved itself with no action from me, I dont know how, perhaps kaspersky updated and sorted itself out on its own!