diff --git a/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/ManagedIndexCoordinator.kt b/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/ManagedIndexCoordinator.kt
index ae43a4829..c26469907 100644
--- a/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/ManagedIndexCoordinator.kt
+++ b/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/ManagedIndexCoordinator.kt
@@ -297,7 +297,7 @@ class ManagedIndexCoordinator(
             val deletedIndices = event.indicesDeleted().map { it.name }
             val allIndicesUuid = indexMetadataProvider.getMultiTypeISMIndexMetadata(indexNames = deletedIndices).map { (_, metadataMapForType) ->
                 metadataMapForType.values.map { it.indexUuid }
-            }.flatten()
+            }.flatten().toSet()
             // Check if the deleted index uuid is still part of any metadata service in the cluster and has an existing managed index job
             indicesToClean = event.indicesDeleted().filter { it.uuid in managedIndices.keys && !allIndicesUuid.contains(it.uuid) }
             removeManagedIndexReq = indicesToClean.map { deleteManagedIndexRequest(it.uuid) }
diff --git a/src/main/resources/mappings/opendistro-ism-config.json b/src/main/resources/mappings/opendistro-ism-config.json
index bf2b61e1c..f6461c80d 100644
--- a/src/main/resources/mappings/opendistro-ism-config.json
+++ b/src/main/resources/mappings/opendistro-ism-config.json
@@ -1,6 +1,6 @@
 {
   "_meta" : {
-    "schema_version": 14
+    "schema_version": 15
   },
   "dynamic": "strict",
   "properties": {
diff --git a/src/test/kotlin/org/opensearch/indexmanagement/IndexManagementRestTestCase.kt b/src/test/kotlin/org/opensearch/indexmanagement/IndexManagementRestTestCase.kt
index fbe64cf8a..63ee4181c 100644
--- a/src/test/kotlin/org/opensearch/indexmanagement/IndexManagementRestTestCase.kt
+++ b/src/test/kotlin/org/opensearch/indexmanagement/IndexManagementRestTestCase.kt
@@ -27,7 +27,7 @@ import javax.management.remote.JMXServiceURL
 
 abstract class IndexManagementRestTestCase : ODFERestTestCase() {
 
-    val configSchemaVersion = 14
+    val configSchemaVersion = 15
     val historySchemaVersion = 5
 
     // Having issues with tests leaking into other tests and mappings being incorrect and they are not caught by any pending task wait check as
diff --git a/src/test/resources/mappings/cached-opendistro-ism-config.json b/src/test/resources/mappings/cached-opendistro-ism-config.json
index bf2b61e1c..f6461c80d 100644
--- a/src/test/resources/mappings/cached-opendistro-ism-config.json
+++ b/src/test/resources/mappings/cached-opendistro-ism-config.json
@@ -1,6 +1,6 @@
 {
   "_meta" : {
-    "schema_version": 14
+    "schema_version": 15
   },
   "dynamic": "strict",
   "properties": {