if there is more cold weather than sometime finger recognition failed. happened with me before, then i rub the finger and place on censor and it works..!!!
Kindly follow the below mentioned steps to resolve the issue- > If any screen guard/tampered glass/protection film is available then first disable the fingerprint settings and then remove the screen guard. > Once screen guard is removed now register the fingerprint again and check the issue > Make sure to use the central fingerprint parts evenly when you register or scan fingerprint, so that all portions of fingerprint, including the center and corners have been fully scanned.
Nevertheless if you still have similar problems while registering or scanning your fingerprints, please visit to the authorized Samsung service center with device and have it inspected for further resolution. For address details of Samsung Service centers follow the link mentioned below- http://www.samsung.com/in/support/servicelocation/
