diff --git a/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportRollupAction.java b/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportRollupAction.java
index a6014c7e9cd25..f9192772ea1e5 100644
--- a/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportRollupAction.java
+++ b/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportRollupAction.java
@@ -594,32 +594,33 @@ private void createRollupIndex(
         DownsampleAction.Request request,
         ActionListener<AcknowledgedResponse> listener
     ) {
+        /*
+         * When creating the rollup index, we copy the index.number_of_shards from source index,
+         * and we set the index.number_of_replicas to 0, to avoid replicating the index being built.
+         * Also, we set the index.refresh_interval to -1.
+         * We will set the correct number of replicas and refresh the index later.
+         *
+         * We should note that there is a risk of losing a node during the rollup process. In this
+         * case rollup will fail.
+         */
+        Settings.Builder builder = Settings.builder()
+            .put(IndexMetadata.SETTING_INDEX_HIDDEN, true)
+            .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, sourceIndexMetadata.getNumberOfShards())
+            .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0)
+            .put(IndexSettings.INDEX_REFRESH_INTERVAL_SETTING.getKey(), "-1")
+            .put(IndexMetadata.INDEX_DOWNSAMPLE_STATUS.getKey(), IndexMetadata.DownsampleTaskStatus.STARTED);
+        if (sourceIndexMetadata.getSettings().hasValue(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())) {
+            builder.put(
+                MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey(),
+                sourceIndexMetadata.getSettings().get(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())
+            );
+        }
+
         CreateIndexClusterStateUpdateRequest createIndexClusterStateUpdateRequest = new CreateIndexClusterStateUpdateRequest(
             "rollup",
             rollupIndexName,
             rollupIndexName
-        ).settings(
-            /*
-             * When creating the rollup index, we copy the index.number_of_shards from source index,
-             * and we set the index.number_of_replicas to 0, to avoid replicating the index being built.
-             * Also, we set the index.refresh_interval to -1.
-             * We will set the correct number of replicas and refresh the index later.
-             *
-             * We should note that there is a risk of losing a node during the rollup process. In this
-             * case rollup will fail.
-             */
-            Settings.builder()
-                .put(IndexMetadata.SETTING_INDEX_HIDDEN, true)
-                .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, sourceIndexMetadata.getNumberOfShards())
-                .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0)
-                .put(IndexSettings.INDEX_REFRESH_INTERVAL_SETTING.getKey(), "-1")
-                .put(IndexMetadata.INDEX_DOWNSAMPLE_STATUS.getKey(), IndexMetadata.DownsampleTaskStatus.STARTED)
-                .put(
-                    MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey(),
-                    sourceIndexMetadata.getSettings().get(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())
-                )
-                .build()
-        ).mappings(mapping);
+        ).settings(builder.build()).mappings(mapping);
         clusterService.submitStateUpdateTask("create-rollup-index [" + rollupIndexName + "]", new RollupClusterStateUpdateTask(listener) {
             @Override
             public ClusterState execute(ClusterState currentState) throws Exception {
diff --git a/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/downsample/DownsampleActionSingleNodeTests.java b/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/downsample/DownsampleActionSingleNodeTests.java
index f075a986334ee..f7078c5fba367 100644
--- a/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/downsample/DownsampleActionSingleNodeTests.java
+++ b/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/downsample/DownsampleActionSingleNodeTests.java
@@ -840,70 +840,73 @@ private void assertFieldMappings(
     }
 
     private void assertRollupIndexSettings(String sourceIndex, String rollupIndex, GetIndexResponse indexSettingsResp) {
+        Settings sourceSettings = indexSettingsResp.settings().get(sourceIndex);
+        Settings rollupSettings = indexSettingsResp.settings().get(rollupIndex);
+
         // Assert rollup metadata are set in index settings
-        assertEquals("success", indexSettingsResp.getSetting(rollupIndex, IndexMetadata.INDEX_DOWNSAMPLE_STATUS_KEY));
+        assertEquals("success", rollupSettings.get(IndexMetadata.INDEX_DOWNSAMPLE_STATUS_KEY));
 
-        assertNotNull(indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_INDEX_UUID));
-        assertNotNull(indexSettingsResp.getSetting(rollupIndex, IndexMetadata.INDEX_DOWNSAMPLE_SOURCE_UUID_KEY));
+        assertNotNull(sourceSettings.get(IndexMetadata.SETTING_INDEX_UUID));
+        assertNotNull(rollupSettings.get(IndexMetadata.INDEX_DOWNSAMPLE_SOURCE_UUID_KEY));
         assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_INDEX_UUID),
-            indexSettingsResp.getSetting(rollupIndex, IndexMetadata.INDEX_DOWNSAMPLE_SOURCE_UUID_KEY)
+            sourceSettings.get(IndexMetadata.SETTING_INDEX_UUID),
+            rollupSettings.get(IndexMetadata.INDEX_DOWNSAMPLE_SOURCE_UUID_KEY)
         );
 
-        assertEquals(sourceIndex, indexSettingsResp.getSetting(rollupIndex, IndexMetadata.INDEX_DOWNSAMPLE_SOURCE_NAME_KEY));
-        assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexSettings.MODE.getKey()),
-            indexSettingsResp.getSetting(rollupIndex, IndexSettings.MODE.getKey())
-        );
+        assertEquals(sourceIndex, rollupSettings.get(IndexMetadata.INDEX_DOWNSAMPLE_SOURCE_NAME_KEY));
+        assertEquals(sourceSettings.get(IndexSettings.MODE.getKey()), rollupSettings.get(IndexSettings.MODE.getKey()));
 
-        assertNotNull(indexSettingsResp.getSetting(sourceIndex, IndexSettings.TIME_SERIES_START_TIME.getKey()));
-        assertNotNull(indexSettingsResp.getSetting(rollupIndex, IndexSettings.TIME_SERIES_START_TIME.getKey()));
+        assertNotNull(sourceSettings.get(IndexSettings.TIME_SERIES_START_TIME.getKey()));
+        assertNotNull(rollupSettings.get(IndexSettings.TIME_SERIES_START_TIME.getKey()));
         assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexSettings.TIME_SERIES_START_TIME.getKey()),
-            indexSettingsResp.getSetting(rollupIndex, IndexSettings.TIME_SERIES_START_TIME.getKey())
+            sourceSettings.get(IndexSettings.TIME_SERIES_START_TIME.getKey()),
+            rollupSettings.get(IndexSettings.TIME_SERIES_START_TIME.getKey())
         );
 
-        assertNotNull(indexSettingsResp.getSetting(sourceIndex, IndexSettings.TIME_SERIES_END_TIME.getKey()));
-        assertNotNull(indexSettingsResp.getSetting(rollupIndex, IndexSettings.TIME_SERIES_END_TIME.getKey()));
+        assertNotNull(sourceSettings.get(IndexSettings.TIME_SERIES_END_TIME.getKey()));
+        assertNotNull(rollupSettings.get(IndexSettings.TIME_SERIES_END_TIME.getKey()));
         assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexSettings.TIME_SERIES_END_TIME.getKey()),
-            indexSettingsResp.getSetting(rollupIndex, IndexSettings.TIME_SERIES_END_TIME.getKey())
+            sourceSettings.get(IndexSettings.TIME_SERIES_END_TIME.getKey()),
+            rollupSettings.get(IndexSettings.TIME_SERIES_END_TIME.getKey())
         );
-        assertNotNull(indexSettingsResp.getSetting(sourceIndex, IndexMetadata.INDEX_ROUTING_PATH.getKey()));
-        assertNotNull(indexSettingsResp.getSetting(rollupIndex, IndexMetadata.INDEX_ROUTING_PATH.getKey()));
+        assertNotNull(sourceSettings.get(IndexMetadata.INDEX_ROUTING_PATH.getKey()));
+        assertNotNull(rollupSettings.get(IndexMetadata.INDEX_ROUTING_PATH.getKey()));
         assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexMetadata.INDEX_ROUTING_PATH.getKey()),
-            indexSettingsResp.getSetting(rollupIndex, IndexMetadata.INDEX_ROUTING_PATH.getKey())
+            sourceSettings.get(IndexMetadata.INDEX_ROUTING_PATH.getKey()),
+            rollupSettings.get(IndexMetadata.INDEX_ROUTING_PATH.getKey())
         );
 
-        assertNotNull(indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_NUMBER_OF_SHARDS));
-        assertNotNull(indexSettingsResp.getSetting(rollupIndex, IndexMetadata.SETTING_NUMBER_OF_SHARDS));
+        assertNotNull(sourceSettings.get(IndexMetadata.SETTING_NUMBER_OF_SHARDS));
+        assertNotNull(rollupSettings.get(IndexMetadata.SETTING_NUMBER_OF_SHARDS));
         assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_NUMBER_OF_SHARDS),
-            indexSettingsResp.getSetting(rollupIndex, IndexMetadata.SETTING_NUMBER_OF_SHARDS)
+            sourceSettings.get(IndexMetadata.SETTING_NUMBER_OF_SHARDS),
+            rollupSettings.get(IndexMetadata.SETTING_NUMBER_OF_SHARDS)
         );
 
-        assertNotNull(indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_NUMBER_OF_REPLICAS));
-        assertNotNull(indexSettingsResp.getSetting(rollupIndex, IndexMetadata.SETTING_NUMBER_OF_REPLICAS));
-        assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_NUMBER_OF_REPLICAS),
-            indexSettingsResp.getSetting(rollupIndex, IndexMetadata.SETTING_NUMBER_OF_REPLICAS)
-        );
-        assertEquals("true", indexSettingsResp.getSetting(rollupIndex, IndexMetadata.SETTING_BLOCKS_WRITE));
+        assertNotNull(sourceSettings.get(IndexMetadata.SETTING_NUMBER_OF_REPLICAS));
+        assertNotNull(rollupSettings.get(IndexMetadata.SETTING_NUMBER_OF_REPLICAS));
         assertEquals(
-            indexSettingsResp.getSetting(sourceIndex, IndexMetadata.SETTING_INDEX_HIDDEN),
-            indexSettingsResp.getSetting(rollupIndex, IndexMetadata.SETTING_INDEX_HIDDEN)
+            sourceSettings.get(IndexMetadata.SETTING_NUMBER_OF_REPLICAS),
+            rollupSettings.get(IndexMetadata.SETTING_NUMBER_OF_REPLICAS)
         );
 
-        if (indexSettingsResp.getSetting(sourceIndex, MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()) != null) {
+        assertEquals("true", rollupSettings.get(IndexMetadata.SETTING_BLOCKS_WRITE));
+        assertEquals(sourceSettings.get(IndexMetadata.SETTING_INDEX_HIDDEN), rollupSettings.get(IndexMetadata.SETTING_INDEX_HIDDEN));
+
+        if (sourceSettings.keySet().contains(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())) {
             assertNotNull(indexSettingsResp.getSetting(rollupIndex, MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()));
         }
-        if (indexSettingsResp.getSetting(sourceIndex, MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()) != null
-            && indexSettingsResp.getSetting(rollupIndex, MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()) != null)
+
+        if (sourceSettings.keySet().contains(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())
+            && rollupSettings.keySet().contains(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())) {
             assertEquals(
-                indexSettingsResp.getSetting(sourceIndex, MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()),
-                indexSettingsResp.getSetting(rollupIndex, MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())
+                sourceSettings.get(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()),
+                rollupSettings.get(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey())
             );
+        } else {
+            assertFalse(sourceSettings.keySet().contains(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()));
+            assertFalse(rollupSettings.keySet().contains(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING.getKey()));
+        }
     }
 
     private AggregationBuilder buildAggregations(