Comment 4 for bug 1817897

So, whether or not I needed to run pam-auth-update, doing so and enabling fingerprint authentication there should not cause GDM to break, nor should the other weird behavior I described above be happening.

Having said that, yes, I was trying to enable login with fingerprint. I googled how to do that on Ubuntu and found this page, https://help.ubuntu.com/stable/ubuntu-help/session-fingerprint.html.en. But when I followed the instructions there and opened the Users panel, there was nothing there about fingerprint login. So I googled more and found this page, https://askubuntu.com/questions/1049526/fingerprint-activation-on-ubuntu-18-04, which mentioned using pam-auth-update to ensure that fingerprint authentication was enabled. So I ran pam-auth-update and found that it wasn't enabled and enabled it, which led to the problems described above.

If I shouldn't have had to do any of that to be able to configure fingerprint login, then something else is wrong and I don't even know where to start looking to figure out what, but regardless of that, the issues that I encountered with pam-auth-update behaving poorly are still real.