I still run 4.4.4 because all the tools I want play nicely on it; I’m not missing out on “updates” with ota crippled and #PrivacyRape removed.
Last night the phone inexplicably didn’t show fingerprint option on lock screen after sitting on about a week which is nothing unusual instead prompting for a ‘backup password’ that while I remembered it the phone did not agree I was correct.
Short version fix assumes root and adb enabled
while booted to recovery
remove from /data/system
Long version fix involves explanations, reading lists, backups.