Galaxy J5/J7 2017: Basic operation > Sometimes my device does not recognize my fingerprint

Q: Sometimes my device doesn’t recognize my fingerprint. What should I do?
 
When you scan your fingerprints on the device, be aware of the following conditions that may affect the feature’s performance: 
• The fingerprint recognition sensor recognizes fingerprints. Ensure that the fingerprint recognition sensor is not scratched or damaged by metal objects, such as coins, keys, and necklaces. 
• The screen protector supplied with the device may cause the fingerprint recognition sensor to malfunction. Remove the screen protector to improve fingerprint sensitivity. 
• Ensure that the fingerprint recognition area and your fingers are clean and dry. 
• The device may not recognize fingerprints that are affected by wrinkles or scars. 
• The device may not recognize fingerprints from small or thin fingers. 
• If you bend your finger or use a fingertip, the device may not recognize your fingerprints. Make sure to cover the entire fingerprint recognition sensor with your finger. 
• To improve recognition performance, register fingerprints of the hand used most often to perform tasks on the device. 
• In dry environments, static electricity can build up in the device. Avoid using this feature in dry environments or before using the feature, discharge static electricity by touching a metal object.

For best results, while registering, for entire enrollment please cover entire fingerprint recognition sensor with your fingerprint and cover fingerprint recognition sensor with your fingerprint partially at least 80% for partial enrollment. And keep your finger flat against the home key and lift it up at a moderate speed. 
The fingerprint sensor is sensitive to moisture, so make sure both the screen and your fingertip are dry.