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.