diff --git a/libraries/session/src/main/java/androidx/media3/session/DefaultActionFactory.java b/libraries/session/src/main/java/androidx/media3/session/DefaultActionFactory.java
index fff79f9eeb..bcc1205922 100644
--- a/libraries/session/src/main/java/androidx/media3/session/DefaultActionFactory.java
+++ b/libraries/session/src/main/java/androidx/media3/session/DefaultActionFactory.java
@@ -65,7 +65,7 @@ import androidx.media3.common.util.Util;
     intent.setComponent(new ComponentName(service, service.getClass()));
     intent.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_DOWN, keyCode));
     if (Util.SDK_INT >= 26 && command != COMMAND_PAUSE && command != COMMAND_STOP) {
-      return Api26.createPendingIntent(service, /* requestCode= */ keyCode, intent);
+      return Api26.createPendingIntent(service, keyCode, intent);
     } else {
       return PendingIntent.getService(
           service,
@@ -80,16 +80,12 @@ import androidx.media3.common.util.Util;
     intent.setComponent(new ComponentName(service, service.getClass()));
     intent.putExtra(EXTRAS_KEY_ACTION_CUSTOM, action);
     intent.putExtra(EXTRAS_KEY_ACTION_CUSTOM_EXTRAS, extras);
-    if (Util.SDK_INT >= 26) {
-      return Api26.createPendingIntent(
-          service, /* requestCode= */ KeyEvent.KEYCODE_UNKNOWN, intent);
-    } else {
-      return PendingIntent.getService(
-          service,
-          /* requestCode= */ KeyEvent.KEYCODE_UNKNOWN,
-          intent,
-          Util.SDK_INT >= 23 ? PendingIntent.FLAG_IMMUTABLE : 0);
-    }
+    // Custom actions always start the service in the background.
+    return PendingIntent.getService(
+        service,
+        /* requestCode= */ KeyEvent.KEYCODE_UNKNOWN,
+        intent,
+        Util.SDK_INT >= 23 ? PendingIntent.FLAG_IMMUTABLE : 0);
   }
 
   /** Returns whether {@code intent} was part of a {@link #createMediaAction media action}. */
diff --git a/libraries/session/src/main/java/androidx/media3/session/MediaSessionService.java b/libraries/session/src/main/java/androidx/media3/session/MediaSessionService.java
index fb9a33227d..f2a0ca9fc3 100644
--- a/libraries/session/src/main/java/androidx/media3/session/MediaSessionService.java
+++ b/libraries/session/src/main/java/androidx/media3/session/MediaSessionService.java
@@ -339,10 +339,19 @@ public abstract class MediaSessionService extends Service {
       }
     } else if (actionFactory.isCustomAction(intent)) {
       @Nullable String customAction = actionFactory.getCustomAction(intent);
-      if (session != null && customAction != null) {
-        Bundle customExtras = actionFactory.getCustomActionExtras(intent);
-        getMediaNotificationManager().onCustomAction(session, customAction, customExtras);
+      if (customAction == null) {
+        return START_STICKY;
       }
+      if (session == null) {
+        ControllerInfo controllerInfo = ControllerInfo.createLegacyControllerInfo();
+        session = onGetSession(controllerInfo);
+        if (session == null) {
+          return START_STICKY;
+        }
+        addSession(session);
+      }
+      Bundle customExtras = actionFactory.getCustomActionExtras(intent);
+      getMediaNotificationManager().onCustomAction(session, customAction, customExtras);
     }
     return START_STICKY;
   }