diff --git a/core/res/res/values/config.xml b/core/res/res/values/config.xml
index 4a5df99b63774..e9ba92fe95892 100644
--- a/core/res/res/values/config.xml
+++ b/core/res/res/values/config.xml
@@ -4247,7 +4247,7 @@
     <string translatable="false" name="config_defaultRingtoneVibrationSound"></string>
 
     <!-- Default number of notifications from the same app before they are automatically grouped by the OS -->
-    <integer translatable="false" name="config_autoGroupAtCount">4</integer>
+    <integer translatable="false" name="config_autoGroupAtCount">2</integer>
 
     <!-- The OEM specified sensor type for the lift trigger to launch the camera app. -->
     <integer name="config_cameraLiftTriggerSensorType">-1</integer>
diff --git a/services/core/java/com/android/server/notification/PreferencesHelper.java b/services/core/java/com/android/server/notification/PreferencesHelper.java
index 5e333daed7d9d..05f000c607d84 100644
--- a/services/core/java/com/android/server/notification/PreferencesHelper.java
+++ b/services/core/java/com/android/server/notification/PreferencesHelper.java
@@ -101,6 +101,8 @@ public class PreferencesHelper implements RankingConfig {
 
     @VisibleForTesting
     static final int NOTIFICATION_CHANNEL_COUNT_LIMIT = 50000;
+    @VisibleForTesting
+    static final int NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT = 50000;
 
     private static final int NOTIFICATION_PREFERENCES_PULL_LIMIT = 1000;
     private static final int NOTIFICATION_CHANNEL_PULL_LIMIT = 2000;
@@ -254,6 +256,7 @@ public class PreferencesHelper implements RankingConfig {
                                 }
                             }
                             boolean skipWarningLogged = false;
+                            boolean skipGroupWarningLogged = false;
                             boolean hasSAWPermission = false;
                             if (upgradeForBubbles && uid != UNKNOWN_UID) {
                                 hasSAWPermission = mAppOps.noteOpNoThrow(
@@ -303,6 +306,14 @@ public class PreferencesHelper implements RankingConfig {
                                 String tagName = parser.getName();
                                 // Channel groups
                                 if (TAG_GROUP.equals(tagName)) {
+                                    if (r.groups.size() >= NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT) {
+                                        if (!skipGroupWarningLogged) {
+                                            Slog.w(TAG, "Skipping further groups for " + r.pkg
+                                                    + "; app has too many");
+                                            skipGroupWarningLogged = true;
+                                        }
+                                        continue;
+                                    }
                                     String id = parser.getAttributeValue(null, ATT_ID);
                                     CharSequence groupName = parser.getAttributeValue(null,
                                             ATT_NAME);
@@ -867,6 +878,9 @@ public class PreferencesHelper implements RankingConfig {
             }
             if (fromTargetApp) {
                 group.setBlocked(false);
+                if (r.groups.size() >= NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT) {
+                    throw new IllegalStateException("Limit exceed; cannot create more groups");
+                }
             }
             final NotificationChannelGroup oldGroup = r.groups.get(group.getId());
             if (oldGroup != null) {
diff --git a/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java b/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java
index b48c9c3d4bcc0..736fbd9d50efb 100644
--- a/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java
+++ b/services/tests/uiservicestests/src/com/android/server/notification/PreferencesHelperTest.java
@@ -46,6 +46,7 @@ import static com.android.os.AtomsProto.PackageNotificationChannelPreferences.IS
 import static com.android.os.AtomsProto.PackageNotificationChannelPreferences.UID_FIELD_NUMBER;
 import static com.android.server.notification.PreferencesHelper.DEFAULT_BUBBLE_PREFERENCE;
 import static com.android.server.notification.PreferencesHelper.NOTIFICATION_CHANNEL_COUNT_LIMIT;
+import static com.android.server.notification.PreferencesHelper.NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT;
 import static com.android.server.notification.PreferencesHelper.UNKNOWN_UID;
 
 import static com.google.common.truth.Truth.assertThat;
@@ -4249,6 +4250,52 @@ public class PreferencesHelperTest extends UiServiceTestCase {
         assertNull(mHelper.getNotificationChannel(PKG_O, UID_O, extraChannel1, true));
     }
 
+    @Test
+    public void testTooManyGroups() {
+        for (int i = 0; i < NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT; i++) {
+            NotificationChannelGroup group = new NotificationChannelGroup(String.valueOf(i),
+                    String.valueOf(i));
+            mHelper.createNotificationChannelGroup(PKG_O, UID_O, group, true);
+        }
+        try {
+            NotificationChannelGroup group = new NotificationChannelGroup(
+                    String.valueOf(NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT),
+                    String.valueOf(NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT));
+            mHelper.createNotificationChannelGroup(PKG_O, UID_O, group, true);
+            fail("Allowed to create too many notification channel groups");
+        } catch (IllegalStateException e) {
+            // great
+        }
+    }
+
+    @Test
+    public void testTooManyGroups_xml() throws Exception {
+        String extraGroup = "EXTRA";
+        String extraGroup1 = "EXTRA1";
+
+        // create first... many... directly so we don't need a big xml blob in this test
+        for (int i = 0; i < NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT; i++) {
+            NotificationChannelGroup group = new NotificationChannelGroup(String.valueOf(i),
+                    String.valueOf(i));
+            mHelper.createNotificationChannelGroup(PKG_O, UID_O, group, true);
+        }
+
+        final String xml = "<ranking version=\"1\">\n"
+                + "<package name=\"" + PKG_O + "\" uid=\"" + UID_O + "\" >\n"
+                + "<channelGroup id=\"" + extraGroup + "\" name=\"hi\"/>"
+                + "<channelGroup id=\"" + extraGroup1 + "\" name=\"hi2\"/>"
+                + "</package>"
+                + "</ranking>";
+        TypedXmlPullParser parser = Xml.newFastPullParser();
+        parser.setInput(new BufferedInputStream(new ByteArrayInputStream(xml.getBytes())),
+                null);
+        parser.nextTag();
+        mHelper.readXml(parser, false, UserHandle.USER_ALL);
+
+        assertNull(mHelper.getNotificationChannelGroup(extraGroup, PKG_O, UID_O));
+        assertNull(mHelper.getNotificationChannelGroup(extraGroup1, PKG_O, UID_O));
+    }
+
     @Test
     public void testRestoreMultiUser() throws Exception {
         String pkg = "restore_pkg";