diff --git a/server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java b/server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java
index 0fda2f04ac5a4..d79e63672aee3 100644
--- a/server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java
+++ b/server/src/main/java/org/elasticsearch/index/engine/InternalEngine.java
@@ -41,7 +41,6 @@
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.LockObtainFailedException;
 import org.apache.lucene.util.BytesRef;
-import org.elasticsearch.core.internal.io.IOUtils;
 import org.apache.lucene.util.InfoStream;
 import org.elasticsearch.ExceptionsHelper;
 import org.elasticsearch.Version;
@@ -59,6 +58,7 @@
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.util.concurrent.AbstractRunnable;
 import org.elasticsearch.common.util.concurrent.ReleasableLock;
+import org.elasticsearch.core.internal.io.IOUtils;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.VersionType;
 import org.elasticsearch.index.mapper.IdFieldMapper;
@@ -188,8 +188,7 @@ public InternalEngine(EngineConfig engineConfig) {
                     translog::getLastSyncedGlobalCheckpoint, startingCommit);
                 writer = createWriter(startingCommit);
                 bootstrapAppendOnlyInfoFromWriter(writer);
-                historyUUID = loadOrGenerateHistoryUUID(writer);
-                Objects.requireNonNull(historyUUID, "history uuid should not be null");
+                historyUUID = loadHistoryUUID(writer);
                 indexWriter = writer;
             } catch (IOException | TranslogCorruptedException e) {
                 throw new EngineCreationFailureException(shardId, "failed to create engine", e);
@@ -278,10 +277,11 @@ protected IndexSearcher refreshIfNeeded(IndexSearcher referenceToRefresh) throws
             // steal it by calling incRef on the "stolen" reader
             internalSearcherManager.maybeRefreshBlocking();
             IndexSearcher acquire = internalSearcherManager.acquire();
-            final IndexReader previousReader = referenceToRefresh.getIndexReader();
-            assert previousReader instanceof ElasticsearchDirectoryReader:
-                "searcher's IndexReader should be an ElasticsearchDirectoryReader, but got " + previousReader;
             try {
+                final IndexReader previousReader = referenceToRefresh.getIndexReader();
+                assert previousReader instanceof ElasticsearchDirectoryReader:
+                    "searcher's IndexReader should be an ElasticsearchDirectoryReader, but got " + previousReader;
+
                 final IndexReader newReader = acquire.getIndexReader();
                 if (newReader == previousReader) {
                     // nothing has changed - both ref managers share the same instance so we can use reference equality
@@ -501,7 +501,7 @@ private String loadTranslogUUIDFromLastCommit() throws IOException {
     /**
      * Reads the current stored history ID from the IW commit data.
      */
-    private String loadOrGenerateHistoryUUID(final IndexWriter writer) throws IOException {
+    private String loadHistoryUUID(final IndexWriter writer) throws IOException {
         final String uuid = commitDataAsMap(writer).get(HISTORY_UUID_KEY);
         if (uuid == null) {
             throw new IllegalStateException("commit doesn't contain history uuid");