Sometime can't unlock with finger prints.

[aJ7pro1]

Recently I've discovered I can't open my phone sometimes with my finger print, I have to use other unlocking methods (pattern). 
I get the message "draw your pattern as required by the security policy instead of using your fingerprints"

I have started to get this message very recently and I am not using any third-party app for unlocking my device (nova launcher and others).
How to get rid of this? 

Thanks in advance. 

[phantom2]

some times you need to delete your old finger print and register a new one. try that

[aJ7pro1]

Hi Phantom,
I've tried that too. I guess it was all good for a few days then I've started to get this all over again.

[phantom2]

hi aj7pro

unfortunately if that did not work then backup your data and factory reset. and if the problem continues then you most likely to have a hardware problem.

[MissKhan1]

register with the new one

[aJ7pro1]

Hi guys,
It seems the problem recovered itself after my android version updated to 8 from the previous 7.
Thanks a lot everyone for your valuable inputs.
Cheers!