diff --git a/services/core/java/com/android/server/biometrics/AuthSession.java b/services/core/java/com/android/server/biometrics/AuthSession.java
index cc49f07dd0e5d..41ca13f5d5f54 100644
--- a/services/core/java/com/android/server/biometrics/AuthSession.java
+++ b/services/core/java/com/android/server/biometrics/AuthSession.java
@@ -538,13 +538,12 @@ public final class AuthSession implements IBinder.DeathRecipient {
 
     void onDialogAnimatedIn() {
         if (mState != STATE_AUTH_STARTED) {
-            Slog.w(TAG, "onDialogAnimatedIn, unexpected state: " + mState);
+            Slog.e(TAG, "onDialogAnimatedIn, unexpected state: " + mState);
+            return;
         }
 
         mState = STATE_AUTH_STARTED_UI_SHOWING;
-
         startAllPreparedFingerprintSensors();
-        mState = STATE_AUTH_STARTED_UI_SHOWING;
     }
 
     void onTryAgainPressed() {
diff --git a/services/tests/servicestests/src/com/android/server/biometrics/AuthSessionTest.java b/services/tests/servicestests/src/com/android/server/biometrics/AuthSessionTest.java
index 25cf8a86baadd..e95924ad71096 100644
--- a/services/tests/servicestests/src/com/android/server/biometrics/AuthSessionTest.java
+++ b/services/tests/servicestests/src/com/android/server/biometrics/AuthSessionTest.java
@@ -20,7 +20,9 @@ import static android.hardware.biometrics.BiometricAuthenticator.TYPE_FACE;
 import static android.hardware.biometrics.BiometricAuthenticator.TYPE_FINGERPRINT;
 import static android.hardware.biometrics.BiometricPrompt.DISMISSED_REASON_NEGATIVE;
 
-import static com.android.server.biometrics.BiometricServiceStateProto.*;
+import static com.android.server.biometrics.BiometricServiceStateProto.STATE_AUTH_CALLED;
+import static com.android.server.biometrics.BiometricServiceStateProto.STATE_AUTH_STARTED;
+import static com.android.server.biometrics.BiometricServiceStateProto.STATE_AUTH_STARTED_UI_SHOWING;
 
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
@@ -32,6 +34,8 @@ import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -279,6 +283,43 @@ public class AuthSessionTest {
                 session.mPreAuthInfo.eligibleSensors.get(fingerprintSensorId).getSensorState());
     }
 
+    @Test
+    public void testOnDialogAnimatedInDoesNothingDuringInvalidState() throws Exception {
+        setupFingerprint(0 /* id */, FingerprintSensorProperties.TYPE_UDFPS_OPTICAL);
+        final long operationId = 123;
+        final int userId = 10;
+
+        final AuthSession session = createAuthSession(mSensors,
+                false /* checkDevicePolicyManager */,
+                Authenticators.BIOMETRIC_STRONG,
+                TEST_REQUEST_ID,
+                operationId,
+                userId);
+        final IBiometricAuthenticator impl = session.mPreAuthInfo.eligibleSensors.get(0).impl;
+
+        session.goToInitialState();
+        for (BiometricSensor sensor : session.mPreAuthInfo.eligibleSensors) {
+            assertEquals(BiometricSensor.STATE_WAITING_FOR_COOKIE, sensor.getSensorState());
+            session.onCookieReceived(
+                    session.mPreAuthInfo.eligibleSensors.get(sensor.id).getCookie());
+        }
+        assertTrue(session.allCookiesReceived());
+        assertEquals(STATE_AUTH_STARTED, session.getState());
+        verify(impl, never()).startPreparedClient(anyInt());
+
+        // First invocation should start the client monitor.
+        session.onDialogAnimatedIn();
+        assertEquals(STATE_AUTH_STARTED_UI_SHOWING, session.getState());
+        verify(impl).startPreparedClient(anyInt());
+
+        // Subsequent invocations should not start the client monitor again.
+        session.onDialogAnimatedIn();
+        session.onDialogAnimatedIn();
+        session.onDialogAnimatedIn();
+        assertEquals(STATE_AUTH_STARTED_UI_SHOWING, session.getState());
+        verify(impl, times(1)).startPreparedClient(anyInt());
+    }
+
     @Test
     public void testCancelAuthentication_whenStateAuthCalled_invokesCancel()
             throws RemoteException {