/errors/ad_group_error.proto 

--- v20/errors/ad_group_error.proto 2025-08-05 14:39:40.000000000 +0000
+++ v21/errors/ad_group_error.proto 2025-08-05 14:39:46.000000000 +0000
@@ -93,5 +93,16 @@

     // Invalid status for the ad group.
     INVALID_STATUS = 19;
+
+    // For video ads sequencing, AdGroup `step_id` has to use a `step_id`
+    // defined in `campaign.video_campaign_settings.video_ad_sequence`.
+    INVALID_STEP_ID_FOR_VIDEO_ADS_SEQUENCING = 20;
+
+    // For video ads sequencing, AdGroup type has to use a type defined in
+    // `campaign.video_campaign_settings.video_ad_sequence`.
+    INVALID_AD_GROUP_TYPE_FOR_VIDEO_ADS_SEQUENCING = 21;
+
+    // Only one AdGroup is allowed for each step ID in video ads sequencing.
+    DUPLICATE_STEP_ID = 22;
   }
 }