When trying to use quick unlock with biometric data this error sometimes occurs on Android. It might indicate that the keystore got corrupted. The easiest way is probably to clear the application data.
Error while writing quick unlock credentials.
### AuthException: AuthException{code: AuthExceptionCode.unknown, message: Unexpected authentication error. the master key android-keystore://QuickUnlock_master_key exists but is unusable}
This seems to be a bug in some android distributions or in AOSP or in the androidx library.
Some more resources: