S21 FE fingerprint not working randomly

[Paminot]

I set the phone for fingerprint to be active even with display off, so i can unlock my phone without lit my screen,
Randomly, every 20-30 times maybe, fingerprint icon will not lit when i touch it. So i have to turn on display and after this i can unlock with fingerprint. After this again i can unlock my phone with fingerprint with display off, for another 20-30 times.

I try to turn off adaptive battery, no result same problem occur. No other power savings active, by my knowldge at least
I try to reset figerprint by removing and add again. No result. But this not a problem of recognition, my sensor for fingerprint will not lit when i touch. I also perform a clear cahce in ecovery mode. Im on android 13, and maybe this problem comes with this update. The phone works fine for few months and suddendy this problem, cant say if this occur with android 13 update o r few days early on android 12

[Thats_What_She_said]

Sometimes on the lock screen, it will require you to type in the password for your phone to unlock it as a security feature. I don't think it is able to be turned off.

[Paminot]

Not related to this. I touch the screen but fingerprint sensor will not activate to read my thumb. If i wake up scree this will activate sensor to read and i can unlock my phone with fingerprint, not asking for PIN.

Look like somehow the figerprint app enter sleep mode or something. Or maybe is something about whole display. I have set to double tap for screen on and double tap for screen off. Double tap for screen on will work always. Dobule  tap for screen off wil not work sometimes, randomly i have to double tap again to screen off, after this will work by the first try. Strange

Meanwhile i also start phone in safe mode and the phone act the same.

I guess is another bug, very annoying. Any new idea to try sometghig will be appreciated

[Nunyb]

Jsu as Thats_What_She_ said stated. It's a security feature and can't be turned off. Sorry.

[Paminot]

Funny, is not about asking PIN on several unlocks. I know this feature and i know this can not be set to off. Did i mention somewhere wanting to set off this feature ? Or did i mention in my post sometghing about this feature ? I talk about very different things

maybe i did not explain properly. lets try again

I unlock my phone with fingerprint. I can do this with screen off, due to my settings. But sometimes when i touch the screen nothing happens, finger print sensor will not lit, and not asking for PIN. If i lit the screen tapping twice or by power buton i can unlock again with my fingerprint, even if the screen will go off again. And will works this way for tens of times and than stuck again until i lit my screen

[Thats_What_She_said]

In settings, type fingerprint unlock, click that, then on the screen, after you type in the pin, click show fingerprint sensor always, then click show always on always on display.

[Thats_What_She_said]

Use this as a reference. I'm not sure why this is happening to you... it weird.

[Paminot]

Agree is weird 🙂

Finger print always on is set to on. But sometimes act like it was set to off, no response when screen is off. Just sometimes

Show icon when screen is off - for this i try all three settings without any result.  When i set to on on AOD this will not show my fingerprint sensor because i dont use AOD, is set to off. And sure i dont want to display sensor all the time, battery will suffer.  I want that sensor to be active all the time, screen off included but i dont want to be lit all the time.

When i set my icon for fingerprint to be showed on tap this will work for a while, but after tens of unclocking when i tap the sensor and nothing happen then also a tap anywhere on the screen wil not show my icon, like dispay is dead. But in this case if i double tap the screen this wil wake my screen and after this again i can unlock with my fingerprint only even if the screen is of, without asking PIn, pattern or password.

I also set com.samsung.android.biometrics.app.settings to be unrestricted, no result either

Looks like fingerprint sensor sometimes goes to sleep, or maybe the whole display because one tap will not show the sensor. But tapping twice this will wake the screen and also the sensor. Strange indeed.

[Paminot · Accepted solution]

To conclude, this is a bug for sure. I reset my phone to factory setting, i did not install anything and i roam through settings turning on and off. After a while same symptom occur. I dont know if this bug is from Android or Sasung but i dont care anymore.

Thank you for support