diff --git a/plugin/src/main/java/org/opensearch/ml/indices/MLIndicesHandler.java b/plugin/src/main/java/org/opensearch/ml/indices/MLIndicesHandler.java
index 1910170645..af6203f0ef 100644
--- a/plugin/src/main/java/org/opensearch/ml/indices/MLIndicesHandler.java
+++ b/plugin/src/main/java/org/opensearch/ml/indices/MLIndicesHandler.java
@@ -117,7 +117,7 @@ public void initMLIndexIfAbsent(MLIndex index, ActionListener<Boolean> listener)
                                                     internalListener.onFailure(exception);
                                                 }));
                                         } else {
-                                            internalListener.onFailure(new MLException("Failed to update index " + indexName));
+                                            internalListener.onFailure(new MLException("Failed to update index: " + indexName));
                                         }
                                     }, exception -> {
                                         log.error("Failed to update index " + indexName, exception);