While FIDO U2F support was added with the release of Firefox Quantum, the feature is turned off by default. In order to enable U2F support in Firefox Quantum, 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 enable U2F
It’s 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 Firefox Quantum because of a service-specific implementation. Facebook is one such service that does not support U2F within Firefox Quantum.