There's a screenshot of that "Unknown Protocol" error message in this Vice article: https://www.vice.com/en_ca/article/y3m33x/heres-the-shadow-inc-app-that-fai

There's a screenshot of that "Unknown Protocol" error message in this Vice article: https://www.vice.com/en_ca/article/y3m33x/heres-the-shadow-inc-app-that-failed-in-iowa-last-night https://www.vice.com/en_ca/article/y3m33x/heres-the-shadow-i... It (seems to) occur while trying to access a "2nd Factor Authentication" page at auth0.com, and there's a cross through the padlock icon at the bottom of the window.