Why is Keyguard not being Re-enabled?

Question

I have a Service that does background video recording, during which time I disable the Keyguard. When I want to stop recording I stop the service and OnDestroy() is called.

I can see in my trace that ReenableKeyguard() is called. However, the Keyguard is still disabled until I "Force Stop" the host app that starts the Service.

What could be causing the Keyguard from staying disabled when ReenableKeyguard() is called?

This is the code that destroys the Service and Reenables the keyguard. (It's C#/Xamarin but basically the same as Java)

    public override void OnDestroy()
    {
        Tracer.Trace("BackgroundVideoRecorder::OnDestroy();");
        base.OnDestroy();

        try
        {
            camera.Reconnect();
            mediaRecorder.Stop();
            mediaRecorder.Reset();

            camera.StopPreview();
            mediaRecorder.Release();

            camera.Release();
            camera = null;

            if (Common.KeyGuardLocker != null)
            {
                Tracer.Trace("BackgroundVideoRecorder::OnDestroy() - ReenableKeyguard()");
                Common.KeyGuardLocker.ReenableKeyguard();
            }

            windowManager.RemoveView(surfaceView);
        }
        catch (Exception ex)
        {
            Tracer.Trace(ex);
        }
    }

Answer 1

I have the exact same problem and the reason was that i had only permissions to Disable keyguard and not the ones to re-enable it.

android.permission.DISABLE_KEYGUARD android.permission.ENABLE_KEYGUARD