Firefox seems to have a problem on Linux using USB Security Keys. I have two Yubico Security Keys which I use for 2FA. The problem seems to be that Firefox cannot communicate with the USB port, as it doesn't make any difference whether the USB Security Key is plugged in or not, the error returned is always the same and the Security Key does not light up. I believe Firefox's WebAuth code must be fine, as it works on Windows, which is why I think it's some kind of permissions problem. Chrome works perfectly with the Security Keys on my computer. I've used a number of sites (I've listed a couple below) where you can test your Security Key with Firefox on KDE Neon and the error is always "UnknownError: The operation failed for an unknown transient reason": https://www.token2.com/tools/fido2-test/ https://demo.yubico.com/webauthn-technical/registration I cannot log into Bugzilla with GitHub as my GitHub login uses a Security Key as the second factor.