Samsung
Add a Fingerprint on Samsung auf Samsung
Fingerprint unlock speeds up daily use, but Samsung always treats it as a secondary method only.
Before you can enrol a print, the phone needs an active pattern, PIN, or password as a fallback lock. This backup lock kicks in whenever the sensor fails to read your finger, after a restart, or once too many failed attempts trigger a temporary lockout.
To add a fingerprint, open Settings ➔ Biometrics and security ➔ Fingerprints. Enter your current pattern, PIN, or password to confirm it is you. Then tap Add fingerprint and follow the on-screen instructions, lifting and placing your finger repeatedly until the sensor captures the full print.
If the Fingerprints menu stays greyed out, no secondary lock is set yet. Go back, choose a pattern, PIN, or password first, then return to the biometrics menu to continue.
Screen protectors, wet fingers, or a dirty sensor area are the most common reasons enrollment stalls midway. Clean the sensor and your finger, then restart the enrollment from the same menu.