Did you try to use the Microsoft Authenticator app on your mobile device? Although not listed explicitly, any application that can generate the correct TOTP code by scanning the QR code or by entering the otpauth:// link directly in the app. If the code isn't working then make sure that the time is correct within a few seconds as the code is only valid for thirty seconds. You can possibly compare the 6 digit TOTP code with the code generated in another authenticator app. *https://support.mozilla.org/en-US/kb/secure-firefox-account-two-step-authentication *https://support.mozilla.org/en-US/kb/what-if-im-locked-out-two-step-authentication