If that doesn't help, follow the instructions for manually adding the AdGuard certificate to the FireFox storage.

If something like this happens, first try to click the Reinstall Certificate button - you will find it in the Network tab. Since v68, FireFox trusts the system certificates, but you still can face the 'Connection is untrusted' error. Old FireFox versions, as well as browsers based on them, do not trust certificates from the system storage, but only those from their local storage. Potential Security Risk error in Firefox-based browsers This happens most often in Firefox-based browsers like Mozilla Firefox, PaleMoon, Waterfox, etc., or in Yandex.Browser.

But in some cases this is not enough and you may come across warnings or errors. Normally browsers trust the AdGuard certificate once it's added to the system certificate storage during the installation process. You can learn more about why a certificate is required by reading this article. To be able to filter HTTPS-traffic and efficiently block ads and trackers, AdGuard generates a special (and unique) root certificate and installs it into the system storage.

Connection not secure error firefox