If you want to use HTTP/2 for development (and you should), you need to start using URLs like https://localhost:8080. In most cases, this requires adding a self-signed certificate to your certificate ...

See examples/u2f_server.py for a working example of a HTTP server for U2F enrollment and authentication.u2f_server.py can be run as a stand-alone server, and can be used to test a U2F client ...