[10 III] Fingerprint sensor stops working after screen gets turned on, but before unlocking the phone

REPRODUCIBILITY: Happens every 3-10 unlocks, confirmed by a lot of people in other topic
OS VERSION: 4.4.0.68 (Android 11 62.0.A.3.109)
HARDWARE: X10 III
UI LANGUAGE: Polish
REGRESSION: New device implementation, not sure if it was happening in .64

DESCRIPTION:

After turning the screen on by pressing the power button or by putting finger on the fingerprint and it detecting it, it then stops scanning which prevents you to unlock the screen. Sometimes for a few seconds, sometimes indefinitely. It gets reset and problem gets fixed by turning the screen of and back on again. Diagnosing the issue gets much easier by turning debug LEDs on.

PRECONDITIONS:

It is worth to turn on on LED showing that it is actively scanning:
mcetool --enable-led-pattern=PatternScanningFingerprint
and this is useful as well, showing when it recognises the fingerprint:
mcetool --enable-led-pattern=PatternFingerprintAcquired

STEPS TO REPRODUCE:

  1. Enable unlocking using fingerprint
  2. With screen of put your finger on the sensor, so the screen turns on
  3. Put your finger on the sensor again, trying to unlock it
  4. If the bug doesn’t occur turn the screen off and try again 1)

EXPECTED RESULT:

Yellow LED keeps shining after the screen had been turned on and is shining until you unlock the phone, which means it is scanning until you unlock it.

ACTUAL RESULT:

After the screen gets turned on the Yellow LED stops shining and the sensor stops scanning, preventing you to unlock the screen. Sometimes it starts scanning again after a few seconds, sometimes the screen needs to be turned off to work again.

MODIFICATIONS:

None necessary to encounter this bug, has been happening since the beginning.

ADDITIONAL INFORMATION:

Implementing this suggestion - unlocking phone immediately when the fingerprint has been detected, not having you to scan again would make this bug much less problematic, as I never had it not detect my fingerprint with screen off.

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My workaround on my 10 II is to screen off and then screen on with the locking button. After, fingerprint sensor works again. I’ll check later with the LED if it’s really a workaround.

I get this issue as well, quite frequently on Xperia 10 III with .68 on it. At first I thought it was bad positioning of my finger on the sensor, but later I discoveted that no matter how it was placed on the sensor it didn’t work. My ‘solution’ was just to use the pin code instead until this was fixed.

Bug filed to internal tracker, thanks. I’ve also noticed that the X10iii occasionally allows one fingerprint scan, but then displays the ‘clean the sensor’ message and doesn’t respond to any more fingerprints. Might be related if this is happening before the lock screen appears to show the message.

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I confirm, my workaround works.

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