Hello, Can you try clearing the browser's cookies and cache and removing the FPN from Firefox and reinstalling it through fpn.firefox.com? Let me know if that helps, and if it doesn't, can you tell us: - Which version of the Firefox browser are you using? - Do you get an error when visiting Square webpages? - Have you turned on HTTPS Only mode in your Firefox browser? I hope you may find this helpful, and please let me know if the issue persists.