diff --git a/core/java/android/app/Notification.java b/core/java/android/app/Notification.java
index 432d99d80b892..f7bd489153e5d 100644
--- a/core/java/android/app/Notification.java
+++ b/core/java/android/app/Notification.java
@@ -10137,6 +10137,8 @@ public class Notification implements Parcelable
              * {@link Activity#isLaunchedFromBubble()} will return with {@code true}.
              * </p>
              *
+             * Note that the pending intent used here requires PendingIntent.FLAG_MUTABLE.
+             *
              * @throws NullPointerException if intent is null.
              * @throws NullPointerException if icon is null.
              */
diff --git a/services/core/java/com/android/server/notification/NotificationManagerService.java b/services/core/java/com/android/server/notification/NotificationManagerService.java
index 98dee86a2bdf8..fef5e93d6a6b0 100755
--- a/services/core/java/com/android/server/notification/NotificationManagerService.java
+++ b/services/core/java/com/android/server/notification/NotificationManagerService.java
@@ -6606,15 +6606,14 @@ public class NotificationManagerService extends SystemService {
         }
 
         // bubble or inline reply that's immutable?
-        // TODO (b/171418004): renable after app outreach
-        /*if (n.getBubbleMetadata() != null
+        if (n.getBubbleMetadata() != null
                 && n.getBubbleMetadata().getIntent() != null
                 && hasFlag(mAmi.getPendingIntentFlags(
                         n.getBubbleMetadata().getIntent().getTarget()),
                         PendingIntent.FLAG_IMMUTABLE)) {
             throw new IllegalArgumentException(r.getKey() + " Not posted."
                     + " PendingIntents attached to bubbles must be mutable");
-        }*/
+        }
 
         if (n.actions != null) {
             for (Notification.Action action : n.actions) {
diff --git a/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java b/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
index 3869faedcd3c0..c480258c7fd9e 100755
--- a/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
+++ b/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
@@ -7811,8 +7811,7 @@ public class NotificationManagerServiceTest extends UiServiceTestCase {
         inOrder.verify(child).recordDismissalSentiment(anyInt());
     }
 
-    // TODO (b/171418004): renable after app outreach
-    /*@Test
+    @Test
     public void testImmutableBubbleIntent() throws Exception {
         when(mAmi.getPendingIntentFlags(pi1))
                 .thenReturn(FLAG_IMMUTABLE | FLAG_ONE_SHOT);
@@ -7827,7 +7826,7 @@ public class NotificationManagerServiceTest extends UiServiceTestCase {
         } catch (IllegalArgumentException e) {
             // good
         }
-    }*/
+    }
 
     @Test
     public void testMutableBubbleIntent() throws Exception {