Samsung Galaxy Tab A9+ biometric unlock is not working

The checks in more detail

Delete the saved face and register it again in a well-lit room, holding the tablet at the distance the screen suggests, and take the case or glasses off if they interfere. Light and angle matter, because this tablet's front camera sits on the edge of the screen and, when used in landscape with a keyboard case, the camera may be near your hand. Wipe the lens, remove a screen protector that covers the camera and try again.

Register a second appearance if you often wear glasses or a hat, using the Add alternative look option. If the tablet is shared with children, remember that faces can look alike, so set a strong PIN and treat face unlock as a convenience. Check that Settings, Biometrics and security, Face recognition, has Stay on lock screen or Faster recognition settings that suit you, and turn off Require open eyes if you want it to work when you are lying down. Software faults can break the feature. Install the latest update from Settings, Software update, restart the tablet and test.

A third-party lock app or device management policy can block biometrics, and a work profile may require a PIN only. If the camera itself does not work in other apps, the face unlock cannot work either, so test the camera. As a last resort, back up the tablet and use a factory reset, which erases it and sets the feature up afresh. If you have forgotten the PIN, Samsung's Find My Mobile service can unlock a registered tablet remotely. A PIN that you know is the real key to the tablet, so remember it.