When I first experienced this I ignored it. But after some days I noticed that I have to unlock it by pattern lock or password everytime I restart the phone. After unlocking by pattern/password, I was able to use fingerprint.

Why is this so? I am not sure that every Android device has the same issue. Is this a security feature? If yes, why? I mean if this is a security feature the phone must be unlocked by fingerprint as pattern or password can be guessed after some attempts (especially patterns).

There are some threads (see this and this), but they doesn't seem to be very informative.


There is a secure enclave that stores your biometric data. It has to be given your passcode in order to decrypt your biometric data on reboot.

  • but i don't use any encryption on my device. – daya Apr 6 '18 at 13:34
  • But the secure enclave does, using your lock pattern, password, PIN, etc as the encryption key. – Adonalsium Apr 6 '18 at 14:02

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