[Android Central Question]

Locked out of phone
fingerprint function not available message
never set password

[Mooncatt]

To enable the fingerprint, you are required to set up a backup password/PIN. They do this just for that reason of not being able to read a fingerprint correctly, and is also required upon a reboot, which doesn't even offer a fingerprint sign in. So either you did set a password and forgot it, or perhaps you got the phone second hand or someone else had access to it that set up the password.

So right now your only option is to try and remember the password, or factory reset and hope you remember for Google account info because it'll require that when setting up the phone again.