diff --git a/core/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java b/core/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java
index ef381bbcf2f..bb030d82ed7 100644
--- a/core/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java
+++ b/core/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java
@@ -107,6 +107,7 @@ import org.elasticsearch.indices.mapper.MapperRegistry;
 import org.elasticsearch.test.DummyShardLock;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.IndexSettingsModule;
+import org.elasticsearch.test.OldIndexUtils;
 import org.elasticsearch.threadpool.TestThreadPool;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.hamcrest.MatcherAssert;
@@ -123,6 +124,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Base64;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -1790,7 +1792,6 @@ public class InternalEngineTests extends ESTestCase {
         return new Mapping(Version.CURRENT, root, new MetadataFieldMapper[0], emptyMap());
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/21147")
     public void testUpgradeOldIndex() throws IOException {
         List<Path> indexes = new ArrayList<>();
         try (DirectoryStream<Path> stream = Files.newDirectoryStream(getBwcIndicesPath(), "index-*.zip")) {
@@ -1812,18 +1813,19 @@ public class InternalEngineTests extends ESTestCase {
             Path[] list = filterExtraFSFiles(FileSystemUtils.files(unzipDataDir));
 
             if (list.length != 1) {
-                throw new IllegalStateException("Backwards index must contain exactly one cluster but was " + list.length + " " + Arrays.toString(list));
+                throw new IllegalStateException("Backwards index must contain exactly one cluster but was " + list.length
+                    + " " + Arrays.toString(list));
             }
+
             // the bwc scripts packs the indices under this path
-            Path src = list[0].resolve("nodes/0/indices/" + indexName);
-            Path translog = list[0].resolve("nodes/0/indices/" + indexName).resolve("0").resolve("translog");
-            assertTrue("[" + indexFile + "] missing index dir: " + src.toString(), Files.exists(src));
+            Path src = OldIndexUtils.getIndexDir(logger, indexName, indexFile.toString(), list[0]);
+            Path translog = src.resolve("0").resolve("translog");
             assertTrue("[" + indexFile + "] missing translog dir: " + translog.toString(), Files.exists(translog));
             Path[] tlogFiles = filterExtraFSFiles(FileSystemUtils.files(translog));
             assertEquals(Arrays.toString(tlogFiles), tlogFiles.length, 2); // ckp & tlog
             Path tlogFile = tlogFiles[0].getFileName().toString().endsWith("tlog") ? tlogFiles[0] : tlogFiles[1];
-            final long size = Files.size(tlogFiles[0]);
-            logger.debug("upgrading index {} file: {} size: {}", indexName, tlogFiles[0].getFileName(), size);
+            final long size = Files.size(tlogFile);
+            logger.info("upgrading index {} file: {} size: {}", indexName, tlogFiles[0].getFileName(), size);
             Directory directory = newFSDirectory(src.resolve("0").resolve("index"));
             Store store = createStore(directory);
             final int iters = randomIntBetween(0, 2);
@@ -1967,7 +1969,7 @@ public class InternalEngineTests extends ESTestCase {
 
     public static class TranslogHandler extends TranslogRecoveryPerformer {
 
-        private final DocumentMapper docMapper;
+        private final MapperService mapperService;
         public Mapping mappingUpdate = null;
 
         public final AtomicInteger recoveredOps = new AtomicInteger(0);
@@ -1975,7 +1977,6 @@ public class InternalEngineTests extends ESTestCase {
         public TranslogHandler(String indexName, Logger logger) {
             super(new ShardId("test", "_na_", 0), null, logger);
             Settings settings = Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT).build();
-            RootObjectMapper.Builder rootBuilder = new RootObjectMapper.Builder("test");
             Index index = new Index(indexName, "_na_");
             IndexSettings indexSettings = IndexSettingsModule.newIndexSettings(index, settings);
             IndexAnalyzers indexAnalyzers = null;
@@ -1983,14 +1984,14 @@ public class InternalEngineTests extends ESTestCase {
             indexAnalyzers = new IndexAnalyzers(indexSettings, defaultAnalyzer, defaultAnalyzer, defaultAnalyzer, Collections.emptyMap());
             SimilarityService similarityService = new SimilarityService(indexSettings, Collections.emptyMap());
             MapperRegistry mapperRegistry = new IndicesModule(Collections.emptyList()).getMapperRegistry();
-            MapperService mapperService = new MapperService(indexSettings, indexAnalyzers, similarityService, mapperRegistry, () -> null);
-            DocumentMapper.Builder b = new DocumentMapper.Builder(rootBuilder, mapperService);
-            this.docMapper = b.build(mapperService);
+            mapperService = new MapperService(indexSettings, indexAnalyzers, similarityService, mapperRegistry, () -> null);
         }
 
         @Override
         protected DocumentMapperForType docMapper(String type) {
-            return new DocumentMapperForType(docMapper, mappingUpdate);
+            RootObjectMapper.Builder rootBuilder = new RootObjectMapper.Builder(type);
+            DocumentMapper.Builder b = new DocumentMapper.Builder(rootBuilder, mapperService);
+            return new DocumentMapperForType(b.build(mapperService), mappingUpdate);
         }
 
         @Override
diff --git a/test/framework/src/main/java/org/elasticsearch/test/OldIndexUtils.java b/test/framework/src/main/java/org/elasticsearch/test/OldIndexUtils.java
index 01474e6547d..fd7d7a7f03f 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/OldIndexUtils.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/OldIndexUtils.java
@@ -124,12 +124,13 @@ public class OldIndexUtils {
             return src;
         } else {
             final List<Path> indexFolders = new ArrayList<>();
-            try (DirectoryStream<Path> stream = Files.newDirectoryStream(dataDir.resolve("0/indices"))) {
+            try (DirectoryStream<Path> stream = Files.newDirectoryStream(dataDir.resolve("0/indices"),
+                (p) -> p.getFileName().startsWith("extra") == false)) { // extra FS can break this...
                 for (final Path path : stream) {
                     indexFolders.add(path);
                 }
             }
-            assertThat(indexFolders.size(), equalTo(1));
+            assertThat(indexFolders.toString(), indexFolders.size(), equalTo(1));
             final IndexMetaData indexMetaData = IndexMetaData.FORMAT.loadLatestState(logger, indexFolders.get(0));
             assertNotNull(indexMetaData);
             assertThat(indexFolders.get(0).getFileName().toString(), equalTo(indexMetaData.getIndexUUID()));