diff --git a/core/src/main/java/org/elasticsearch/index/translog/Translog.java b/core/src/main/java/org/elasticsearch/index/translog/Translog.java
index 4ca4f57e341..bdbce03bda1 100644
--- a/core/src/main/java/org/elasticsearch/index/translog/Translog.java
+++ b/core/src/main/java/org/elasticsearch/index/translog/Translog.java
@@ -55,7 +55,6 @@ import java.nio.file.StandardCopyOption;
 import java.nio.file.StandardOpenOption;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -826,10 +825,11 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
 
     public static class Index implements Operation {
 
-        public static final int FORMAT_2x = 6; // since 2.0-beta1 and 1.1
-        public static final int FORMAT_AUTO_GENERATED_IDS = 7; // since 5.0.0-beta1
+        public static final int FORMAT_2_X = 6; // since 2.0-beta1 and 1.1
+        public static final int FORMAT_AUTO_GENERATED_IDS = FORMAT_2_X + 1; // since 5.0.0-beta1
         public static final int FORMAT_SEQ_NO = FORMAT_AUTO_GENERATED_IDS + 1; // since 6.0.0
         public static final int SERIALIZATION_FORMAT = FORMAT_SEQ_NO;
+
         private final String id;
         private final long autoGeneratedIdTimestamp;
         private final String type;
@@ -843,7 +843,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
 
         public Index(StreamInput in) throws IOException {
             final int format = in.readVInt(); // SERIALIZATION_FORMAT
-            assert format >= FORMAT_2x : "format was: " + format;
+            assert format >= FORMAT_2_X : "format was: " + format;
             id = in.readString();
             type = in.readString();
             source = in.readBytesReference();
@@ -1018,7 +1018,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
 
     public static class Delete implements Operation {
 
-        private static final int FORMAT_5_X = 3;
+        private static final int FORMAT_5_X = 2;
         private static final int FORMAT_SEQ_NO = FORMAT_5_X + 1;
         public static final int SERIALIZATION_FORMAT = FORMAT_SEQ_NO;
 
@@ -1030,7 +1030,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
 
         public Delete(StreamInput in) throws IOException {
             final int format = in.readVInt();// SERIALIZATION_FORMAT
-            assert format >= SERIALIZATION_FORMAT - 1: "format was: " + format;
+            assert format >= FORMAT_5_X : "format was: " + format;
             uid = new Term(in.readString(), in.readString());
             this.version = in.readLong();
             this.versionType = VersionType.fromValue(in.readByte());