The Galaxy S24+ has a large 6.7 inch screen with an ultrasonic fingerprint reader under it, and the reader is a little lower than many people expect, so a failure to unlock can simply be a thumb landing too high on the long screen. Look for the fingerprint icon on the lock screen and place the thumb over it. If the phone has a screen protector, check that it is the kind designed for ultrasonic readers, because protectors with a gap or the wrong adhesive block the ultrasonic signal;
The checks in more detail
a protector fitted after you registered the fingerprint often requires you to register again. Wet hands do not bother ultrasonic readers as much as optical ones, but a greasy screen or finger can still confuse it, so wipe both. Open Settings, Security and privacy, Biometrics, Fingerprints to see the list. The S24+ lets you add up to several fingerprints, and a good habit is to register the same finger three times, pressing at slightly different angles, so the phone knows the edges as well as the middle.
Turn on Fingerprint always on if you want the sensor to work with the screen off, and check Fingerprint verification for the apps you use. Face recognition is in the same menu and is an alternative, but it is less secure and works worse in dim light. Because the S24+ has a bigger display, many owners use a case with a screen lip, and a lip that overlaps the glass can touch the sensor area and press on the protector; fit the case properly and see whether the problem returns.
After a software update or a restart the phone asks for the PIN, which is normal. If the reader reads slowly, update the software and clear the phone's system cache by restarting. For a persistent fault, run the diagnostics in Samsung Members and contact Samsung, since the sensor is part of the display. Never use an unofficial repair that replaces the screen without recalibrating the sensor, because the reader may refuse to enroll fingerprints afterwards.
Differential
Likely causes of “Samsung Galaxy S24+ biometric unlock is not working”, and how to tell them apart
- 1
A thumb landing above the sensor
What separates it Failures on the long screen
How to confirm Place the thumb over the lock-screen icon
- 2
A protector or case lip over the sensor
What separates it Reads fail after a fit
How to confirm Use a protector made for the sensor and fit the case properly
- 3
A thin registration
What separates it The phone misses edge reads
How to confirm Register the finger three times at different angles
- 4
A restart or update
What separates it The phone asks for the PIN
How to confirm Enter the PIN once
- 5
A display replaced without calibration
What separates it The reader will not enroll
How to confirm Have Samsung repair it
Before you touch a setting
Record this first — changing settings destroys the evidence
- Where the thumb lands
- Whether a protector or case is fitted
- Whether the screen was repaired
- The software version
Try in this order
0 of 6 completedPlace the thumb on the icon
ReversibleCovering the sensor.
Check the protector and case
ReversibleFor overlap.
Register the finger three times
ReversibleAt different angles.
Update and restart
ReversibleThe phone.
Run diagnostics
ReversibleIn Samsung Members.
Contact Samsung
ReversibleIf it fails.
Model-specific
What is true of this model and not of its siblings
- Long screen
- The sensor sits low on the glass.
- Repairs
- Use official ones.
Stop boundary
When this stops being a self-service repair
- !If the sensor fails after a protector check and a new registration, contact Samsung
- !Avoid unofficial screen repairs
- !Remember the PIN
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why does my S24+ fingerprint miss?+
The thumb may land too high on the long screen.
Does the protector matter?+
Yes, use one made for ultrasonic sensors.
How many times should I register a finger?+
Three times, at different angles.
Can a repair break it?+
An uncalibrated screen can refuse to enroll fingerprints.