If your Samsung Galaxy S25 FE's fingerprint scanner suddenly stops recognizing you, it can lock you out of your phone and apps. The good news is this is usually a software hiccup you can fix yourself. Let's start with the most common solution.
First, try a force restart. Press and hold the Volume Down button and the Side button together for about ten seconds. Keep holding until you see the Samsung logo appear on the screen. This simple reboot clears out temporary glitches that can confuse the under-display sensor, and I've seen it solve the problem more often than not.
Clean Your Screen and Finger
This sounds obvious, but it's the most frequent culprit. The ultrasonic sensor under your S25 FE's screen needs a clean surface to read your fingerprint accurately. Any grease, lotion, or dirt on your finger or the screen itself can block the signal.
Wipe your fingertip on your pants and give the lower part of your screen a good clean with a soft, dry microfiber cloth. Avoid using screen cleaners with alcohol, as they can leave a residue that interferes with the sensor.
Check Your Screen Protector
Not all screen protectors play nice with ultrasonic fingerprint sensors. If you recently installed a new one, especially a thick tempered glass model, it might be the reason your scans are failing.
Try removing the protector temporarily to see if your fingerprint works again. If it does, you'll need to look for a protector specifically marketed as compatible with ultrasonic sensors. You'll also need to delete and re-register your fingerprints after changing or removing any screen protection.
Re-register Your Fingerprint
Sometimes the stored fingerprint data gets corrupted. Deleting the old scan and setting it up fresh almost always helps. Go to Settings > Biometrics and security > Fingerprints.
Enter your PIN, password, or pattern to proceed. Tap on the fingerprint giving you trouble and select Remove. Now, tap Add fingerprint and follow the prompts. Press firmly and rotate your finger slowly to capture the edges, just like the animation shows.
Update Your Software
Outdated software can have bugs that affect hardware features like the fingerprint sensor. Samsung regularly releases updates that include fixes for these kinds of issues.
Head to Settings > Software update > Download and install. If an update is available, install it and restart your phone. This is a good habit to get into, as updates can also improve overall system stability and battery life, especially with features like Adaptive Battery.
Clear the System Cache
If the problem started after a recent software update, cached data from the old system might be causing a conflict. Clearing the cache partition is a safe way to clean this out without touching your personal data.
Turn off your S25 FE completely. Now, press and hold the Volume Up button and the Side button. As soon as you feel a vibration or see the Samsung logo, let go of the Side button but keep holding Volume Up until the Android Recovery menu appears.
Use the volume buttons to highlight Wipe cache partition and press the Side button to select it. Confirm, then select Reboot system now when it's done.
Check for App Conflicts in Safe Mode
A recently installed third-party app could be interfering with the biometric system. Booting into Safe Mode temporarily disables all downloaded apps so you can test the fingerprint sensor in isolation.
Press and hold the Side button until the power menu appears. Then, tap and hold the Power off icon until you see the Safe Mode prompt. Tap to restart in Safe Mode. If your fingerprint works perfectly here, you know a downloaded app is the cause. You'll need to uninstall apps one by one to find the offender.
Review Your Fingerprint Settings
There are a couple of settings worth double-checking. First, ensure fingerprint unlock is actually turned on. In Settings > Biometrics and security > Fingerprints, make sure the switch for Fingerprint unlock is enabled.
Also, if you have the "Fingerprint always on" feature enabled, try turning it off. This setting keeps the sensor active even on the lock screen, which can sometimes lead to recognition issues. You'll find this toggle in the same Fingerprint settings menu.
Finally, remember that environmental factors matter. The Exynos chip in the S25 FE can run warm during heavy use, and extreme temperatures, whether hot or cold, can temporarily affect the sensor's performance. If your hands are very dry, the sensor might also struggle. Adding a little moisture can sometimes help it get a better read.