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I have a Thinkpad x1 Carbon (2nd Gen) with a fingerprint scanner. The machine has Kubuntu 22.04 (Jammy Jellyfish) installed.

Since it's Kubuntu, I installed fprintd to scan my fingerprint for login. Here are the commands I ran and things I changed:

$ sudo apt install -y fprintd libpam-fprintd

$ sudo pam-auth-update


$ sudo nano /etc/pam.d/common-auth


Add the below line before the line that starts with “auth [success=1”:


auth [success=2 default=ignore] pam_fprintd.so max_tries=1 timeout=10


Exit and save

When I was ready, I ran fprintd-enroll $my_username

It asked me for my right pointer fingerprint and I swiped my finger. I then received a message saying that my print was enrolled, but nothing happened (as in, the programming kept running), so I kept scanning my finger until the prompts told me that my fingerprint had been logged successfully and the program closed. I then logged out to test it.

Everything up to this point has worked perfectly fine. Installation, input, everything. Here's where the problems arise.

When I tried to log in, the light was blinking green, so clearly the fingerprint scanner was indeed working. However, when I tried to scan my finger again in the exact same way, I just got an error saying that the login failed. Moreover, it wouldn't even process another login attempt until I restarted (I'd just hit enter on the password and nothing would happen, no green light for 'login failed' message). This is likely because I foolishly set the max auth attempts to 1 for the fingerprint scan.

I've been scanning over and over for the last few hours. Is there a way for me to get into my computer without getting the fingerprint to work?

James Li
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  • I haven't tried it with libprintf enabled, but single user mode (adding a 1 to the boot command line) may work. – Didi Kohen Aug 21 '22 at 05:01
  • Thanks. How would I do that? – James Li Aug 21 '22 at 05:07
  • Come to think of it, you may be able to use the console terminal by switching to it with Ctrl+Alt+F3, if not: https://askubuntu.com/questions/132965/how-do-i-boot-into-single-user-mode-from-grub – Didi Kohen Aug 21 '22 at 09:49

2 Answers2

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I had same problem with an X1C4 and Kubuntu 22.04. It broke sudo, so I had to reboot in recovery mode to clear the problem.

  1. Reboot (For some reason it appears Kubuntu allows unprivileged reboot from Konsole)
  2. Select recovery from the Grub menu
  3. Remount the root partition in rw mode: mount -o remount,rw /
  4. Edit /etc/pam.d/common-auth, removing the faulty "auth" lines
  5. Save, reboot.
Dokbua
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  1. CTRL+ALT+F2 on the login screen - terminal will open.
  2. Login 3.sudo pam-auth-update
  3. Deselect "Fingerprint authentication"
  4. Reboot
  5. Login through UI

enter image description here

xx1xx
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