You might want to hold off on trying the iOS 10 beta if you can't bear to be without two-factor sign-ins. At least a handful of users are reporting a two-part problem that has locked them out of their Apple IDs. The first part is a bug with app-specific passwords that can force a password reset, regardless of the iOS version you use. It's not the worst issue if you're using a stable version of iOS, since it takes mere moments to get a new password. Things may go haywire if you're an iOS beta tester with two-factor authentication turned on, however. Users say that Apple's iForgot password system doesn't work for those experimenters, shutting them out of their accounts the moment the app-specific password glitch creeps up.