diff --git a/server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java b/server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java
index e942c4ac2d33c..9c5e640c72216 100644
--- a/server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java
+++ b/server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java
@@ -581,6 +581,9 @@ private void cleanupAfterError(Exception exception) {
     }
 
     private static ShardGenerations buildGenerations(SnapshotsInProgress.Entry snapshot) {
+        if (snapshot.useShardGenerations() == false) {
+            return ShardGenerations.EMPTY;
+        }
         ShardGenerations.Builder builder = ShardGenerations.builder();
         final Map<String, IndexId> indexLookup = new HashMap<>();
         snapshot.indices().forEach(idx -> indexLookup.put(idx.getName(), idx));