diff --git a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PostCalendarEventsAction.java b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PostCalendarEventsAction.java
index 0f4383d00ae..25709db45bf 100644
--- a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PostCalendarEventsAction.java
+++ b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PostCalendarEventsAction.java
@@ -155,8 +155,7 @@ public class PostCalendarEventsAction extends Action<PostCalendarEventsAction.Re
         @Override
         public void readFrom(StreamInput in) throws IOException {
             super.readFrom(in);
-            //TODO version needs to be updated once backport to 6.x
-            if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (in.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag was removed
                 in.readBoolean();
             }
@@ -166,8 +165,7 @@ public class PostCalendarEventsAction extends Action<PostCalendarEventsAction.Re
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            //TODO version needs to be updated once backport to 6.x
-            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (out.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag is no longer supported
                 out.writeBoolean(true);
             }
diff --git a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutCalendarAction.java b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutCalendarAction.java
index e4a6c173154..4781faf1f3d 100644
--- a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutCalendarAction.java
+++ b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutCalendarAction.java
@@ -152,8 +152,7 @@ public class PutCalendarAction extends Action<PutCalendarAction.Request, PutCale
         @Override
         public void readFrom(StreamInput in) throws IOException {
             super.readFrom(in);
-            //TODO version needs to be updated once backport to 6.x
-            if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (in.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag was removed
                 in.readBoolean();
             }
@@ -164,8 +163,7 @@ public class PutCalendarAction extends Action<PutCalendarAction.Request, PutCale
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            //TODO version needs to be updated once backport to 6.x
-            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (out.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag is no longer supported
                 out.writeBoolean(true);
             }
diff --git a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutDatafeedAction.java b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutDatafeedAction.java
index edbd3b5c61b..bb9b9be16e7 100644
--- a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutDatafeedAction.java
+++ b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutDatafeedAction.java
@@ -124,8 +124,7 @@ public class PutDatafeedAction extends Action<PutDatafeedAction.Request, PutData
         @Override
         public void readFrom(StreamInput in) throws IOException {
             super.readFrom(in);
-            //TODO version needs to be updated once backport to 6.x
-            if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (in.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag was removed
                 in.readBoolean();
             }
@@ -135,8 +134,7 @@ public class PutDatafeedAction extends Action<PutDatafeedAction.Request, PutData
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            //TODO version needs to be updated once backport to 6.x
-            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (out.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag is no longer supported
                 out.writeBoolean(true);
             }
diff --git a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutJobAction.java b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutJobAction.java
index ef7669da138..57f4b040010 100644
--- a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutJobAction.java
+++ b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/PutJobAction.java
@@ -149,8 +149,7 @@ public class PutJobAction extends Action<PutJobAction.Request, PutJobAction.Resp
         @Override
         public void readFrom(StreamInput in) throws IOException {
             super.readFrom(in);
-            //TODO version needs to be updated once backport to 6.x
-            if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (in.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag was removed
                 in.readBoolean();
             }
@@ -160,8 +159,7 @@ public class PutJobAction extends Action<PutJobAction.Request, PutJobAction.Resp
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            //TODO version needs to be updated once backport to 6.x
-            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (out.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag is no longer supported
                 out.writeBoolean(true);
             }
diff --git a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/RevertModelSnapshotAction.java b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/RevertModelSnapshotAction.java
index 10c4df1e576..67b362a3359 100644
--- a/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/RevertModelSnapshotAction.java
+++ b/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/action/RevertModelSnapshotAction.java
@@ -178,8 +178,7 @@ extends Action<RevertModelSnapshotAction.Request, RevertModelSnapshotAction.Resp
         @Override
         public void readFrom(StreamInput in) throws IOException {
             super.readFrom(in);
-            //TODO version needs to be updated once backport to 6.x
-            if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (in.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag was removed
                 in.readBoolean();
             }
@@ -189,8 +188,7 @@ extends Action<RevertModelSnapshotAction.Request, RevertModelSnapshotAction.Resp
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            //TODO version needs to be updated once backport to 6.x
-            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1) == false) {
+            if (out.getVersion().before(Version.V_6_3_0)) {
                 //the acknowledged flag is no longer supported
                 out.writeBoolean(true);
             }