I use pam_fprint on my laptop. Somehow my fingerprints disappeared and I could not enroll them back with pam_fprint_enroll. I had this error message:

Enroll failed with error -22

To fix this I switched from pam_fprint to fprintd which uses D-Bus. I also had to change /etc/pam.d/system:

-auth    sufficient   pam_fprint.so
+auth    sufficient   pam_fprintd.so

Then I could enroll my fingerprints with fprint-enroll.