Apple recommends some fixes you may try in your home which may fix the issue if it is due to a software glitch. Those fixes are:

• Make sure your hands are clean and dry. Different sorts of moisturizers may affect the workability of your iPhone. (Such as Oil, lotion, sweat, or water)
• Make sure your iPhone touch ID is clean and wipe it down with a lint-free cloth.
• Make sure you put your entire finger on the home button to make the sensor work.
• Make sure your screen protector or case is not getting in the way of touch ID
• Update your iOS

Also, make sure that Touch ID does not work if you have

• Restarted your phone
• You haven’t unlocked your device in 48 hours
• 5 failed attempts to unlock the phone through touch ID

If your error can’t be categorized or resolved through selective issues and prescribed fixes, you may need to get your phone checked by professional repairmen. Here at ifixit bd, we have experienced professionals who can take care of that for you! ifixit bd which has 4 service points located around Dhaka, Bangladesh, gives you all sorts of iPhone 6 and other iPhone-related solutions for your ease of access.