diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1838db443bd06..2d69aee008586 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -88,6 +88,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix ClassCastException in FlightClientChannel for requests larger than 16KB ([#20010](https://github.com/opensearch-project/OpenSearch/pull/20010))
 - Fix GRPC Bulk ([#19937](https://github.com/opensearch-project/OpenSearch/pull/19937))
 - Fix node bootstrap error when enable stream transport and remote cluster state ([#19948](https://github.com/opensearch-project/OpenSearch/pull/19948))
+- Fix toBuilder method in EngineConfig to include mergedSegmentTransferTracker([20105](https://github.com/opensearch-project/OpenSearch/pull/20105))
 
 ### Dependencies
 - Bump Apache Lucene from 10.3.1 to 10.3.2 ([#20026](https://github.com/opensearch-project/OpenSearch/pull/20026))
diff --git a/server/src/main/java/org/opensearch/index/engine/EngineConfig.java b/server/src/main/java/org/opensearch/index/engine/EngineConfig.java
index 8dab3badefa44..93936b2048b85 100644
--- a/server/src/main/java/org/opensearch/index/engine/EngineConfig.java
+++ b/server/src/main/java/org/opensearch/index/engine/EngineConfig.java
@@ -354,7 +354,8 @@ public Builder toBuilder() {
             .leafSorter(this.leafSorter)
             .documentMapperForTypeSupplier(this.documentMapperForTypeSupplier)
             .indexReaderWarmer(this.indexReaderWarmer)
-            .clusterApplierService(this.clusterApplierService);
+            .clusterApplierService(this.clusterApplierService)
+            .mergedSegmentTransferTracker(this.mergedSegmentTransferTracker);
     }
 
     /**