diff --git a/_about/breaking-changes.md b/_about/breaking-changes.md
index 1070a5f04be..f52762b844f 100644
--- a/_about/breaking-changes.md
+++ b/_about/breaking-changes.md
@@ -54,6 +54,18 @@ The `text_embedding` processor no longer replaces nested values like `_ingest._v
 
 The minimum supported JDK version is JDK 21.
 
+### Version compatibility setting
+
+The `compatibility.override_main_response_version` setting is no longer provided.
+This functionality has been deprecated since OpenSearch 1.x.
+For more information, see issue [#18228](https://github.com/opensearch-project/OpenSearch/issues/18228).
+You can consult [agents and ingestion tools]({{site.url}}{{site.baseurl}}/tools/#agents-and-ingestion-tools) for potential solutions.
+
+### Index version
+
+Indexes (including system ones) that are created in versions older than `2.x.x` are not supported and should be reindexed **before** the upgrade as per [documentation]({{site.url}}{{site.baseurl}}/im-plugin/reindex-data/).
+For more information, see issue [#18717](https://github.com/opensearch-project/OpenSearch/issues/18717).
+
 ### System index access
 
 Access to system indexes through the REST API is no longer provided. This functionality has been deprecated since OpenSearch 1.x. For more information, see issue [#7936](https://github.com/opensearch-project/OpenSearch/issues/7936).