Firefox for Android has been redesigned as of version 80. WebAuthn support and the about:config menu are not currently available in this redesigned version, meaning U2F (and FIDO2) will not work. We are looking into this, and will update this article as we learn more.
Note: As of version 67 Mozilla Firefox now has U2F enabled by default.
Initially when FIDO U2F support was introduced to Firefox, prior to version 67 it was turned off by default. In order to enable U2F support in the older builds, follow the steps below:
- Type "about:config" (without quotes) into the Firefox address bar and press Enter
- Search for “u2f”
- Double-click on security.webauth.u2f to set the value to true. Once set, U2F will be enabled on your browser. Alternatively you can right-click and select Toggle to change the value as well.
If this doesn't work, contact your IT department to determine if there are policies set which prevent users from changing security settings in Mozilla Firefox.
It is important to understand that every FIDO U2F implementation can vary from the official specifications. Some sites supporting FIDO U2F have made accommodations for the incompleteness of Firefox’s implementation, but some have not. In other situations, some services may not work with older versions of Firefox because of a service-specific implementation. Though now enabled by default it is still possible that a service may not work if the service is checking for user-agent (e.g. Firefox) instead of the availability of U2F. For example, Google accounts allow U2F login in Firefox, but require Google Chrome be used to register security keys.