diff --git a/core/src/main/java/org/elasticsearch/index/engine/CombinedDeletionPolicy.java b/core/src/main/java/org/elasticsearch/index/engine/CombinedDeletionPolicy.java
index 6a61843c263e4..e5d8cacf73657 100644
--- a/core/src/main/java/org/elasticsearch/index/engine/CombinedDeletionPolicy.java
+++ b/core/src/main/java/org/elasticsearch/index/engine/CombinedDeletionPolicy.java
@@ -160,9 +160,9 @@ private static int indexOfKeptCommits(List<? extends IndexCommit> commits, long
             if (expectedTranslogUUID.equals(commitUserData.get(Translog.TRANSLOG_UUID_KEY)) == false) {
                 return i + 1;
             }
-            // 5.x commits do not contain MAX_SEQ_NO.
+            // 5.x commits do not contain MAX_SEQ_NO, we should not keep it and the older commits.
             if (commitUserData.containsKey(SequenceNumbers.MAX_SEQ_NO) == false) {
-                return i;
+                return Math.min(commits.size() - 1, i + 1);
             }
             final long maxSeqNoFromCommit = Long.parseLong(commitUserData.get(SequenceNumbers.MAX_SEQ_NO));
             if (maxSeqNoFromCommit <= globalCheckpoint) {
diff --git a/core/src/test/java/org/elasticsearch/index/engine/CombinedDeletionPolicyTests.java b/core/src/test/java/org/elasticsearch/index/engine/CombinedDeletionPolicyTests.java
index ca75c70137b5a..e74cde52aa418 100644
--- a/core/src/test/java/org/elasticsearch/index/engine/CombinedDeletionPolicyTests.java
+++ b/core/src/test/java/org/elasticsearch/index/engine/CombinedDeletionPolicyTests.java
@@ -171,15 +171,15 @@ public void testLegacyIndex() throws Exception {
 
         globalCheckpoint.set(randomLongBetween(0, maxSeqNo - 1));
         indexPolicy.onCommit(Arrays.asList(legacyCommit, freshCommit));
-        verify(legacyCommit, times(0)).delete();
+        verify(legacyCommit, times(1)).delete(); // Do not keep the legacy commit once we have a new commit.
         verify(freshCommit, times(0)).delete();
-        assertThat(translogPolicy.getMinTranslogGenerationForRecovery(), equalTo(legacyTranslogGen));
+        assertThat(translogPolicy.getMinTranslogGenerationForRecovery(), equalTo(safeTranslogGen));
         assertThat(translogPolicy.getTranslogGenerationOfLastCommit(), equalTo(safeTranslogGen));
 
         // Make the fresh commit safe.
         globalCheckpoint.set(randomLongBetween(maxSeqNo, Long.MAX_VALUE));
         indexPolicy.onCommit(Arrays.asList(legacyCommit, freshCommit));
-        verify(legacyCommit, times(1)).delete();
+        verify(legacyCommit, times(2)).delete();
         verify(freshCommit, times(0)).delete();
         assertThat(translogPolicy.getMinTranslogGenerationForRecovery(), equalTo(safeTranslogGen));
         assertThat(translogPolicy.getTranslogGenerationOfLastCommit(), equalTo(safeTranslogGen));