diff --git a/wise-webapp/src/main/java/com/wisemapping/exceptions/MultipleSessionsOpenException.java b/wise-webapp/src/main/java/com/wisemapping/exceptions/MultipleSessionsOpenException.java
index fb4c97e3..6d92a7e0 100755
--- a/wise-webapp/src/main/java/com/wisemapping/exceptions/MultipleSessionsOpenException.java
+++ b/wise-webapp/src/main/java/com/wisemapping/exceptions/MultipleSessionsOpenException.java
@@ -23,7 +23,7 @@ import org.jetbrains.annotations.NotNull;
 public class MultipleSessionsOpenException
     extends ClientException
 {
-    public static final String MSG_KEY = "MINDMAP_TIMESTAMP_OUTDATED";
+    public static final String MSG_KEY = "MINDMAP_OUTDATED_BY_YOU";
 
     public MultipleSessionsOpenException(@NotNull String msg)
     {
@@ -35,9 +35,4 @@ public class MultipleSessionsOpenException
     protected String getMsgBundleKey() {
         return MSG_KEY;
     }
-
-    @Override
-    protected Object[] getMsgBundleArgs() {
-        return new String[]{"you"};
-    }
 }
diff --git a/wise-webapp/src/main/java/com/wisemapping/model/User.java b/wise-webapp/src/main/java/com/wisemapping/model/User.java
index 2b433ad7..d15d86c5 100644
--- a/wise-webapp/src/main/java/com/wisemapping/model/User.java
+++ b/wise-webapp/src/main/java/com/wisemapping/model/User.java
@@ -20,10 +20,10 @@ package com.wisemapping.model;
 
 import org.jetbrains.annotations.Nullable;
 
-import javax.servlet.http.HttpSessionBindingEvent;
-import javax.servlet.http.HttpSessionBindingListener;
 import java.io.Serializable;
-import java.util.*;
+import java.util.Calendar;
+import java.util.HashSet;
+import java.util.Set;
 
 public class User
         extends Collaborator
@@ -107,8 +107,10 @@ public class User
     }
 
     public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
+        if (this == o)
+            return true;
+        if (o == null || !User.class.getClass().isInstance(o))
+            return false;
 
         final User user = (User) o;
 
diff --git a/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java b/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java
index b5b42130..e815f0f9 100644
--- a/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java
+++ b/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java
@@ -192,7 +192,7 @@ public class MindmapController extends BaseController {
                     throw new SessionExpiredException(lastEditor);
                 }
             } else if (outdated) {
-                throw new MultipleSessionsOpenException("The map has been updated and not by you. Session lost.");
+                throw new MultipleSessionsOpenException("Sessions:" + session + ":" + lockInfo.getSession() + "Timestamp: " + timestamp + ": " + lockInfo.getTimestamp());
             }
         } else {
             throw new SessionExpiredException(lockInfo.getUser());
diff --git a/wise-webapp/src/main/resources/messages_en.properties b/wise-webapp/src/main/resources/messages_en.properties
index 99046bba..d331a085 100644
--- a/wise-webapp/src/main/resources/messages_en.properties
+++ b/wise-webapp/src/main/resources/messages_en.properties
@@ -250,6 +250,7 @@ TEMPORAL_PASSWORD_SENT=Your temporal password has been sent
 TEMPORAL_PASSWORD_SENT_DETAILS=We've sent you an email that will allow you to reset your password. Please check your email now.
 TEMPORAL_PASSWORD_SENT_SUPPORT=If you have any problem receiving the email, contact us to  <a href\="mailto\:support@wisemapping.com">support@wisemapping.com </a>
 MINDMAP_TIMESTAMP_OUTDATED=It's not possible to save your changes because your mindmap has been modified by '{0}'. Refresh the page and try again.
+MINDMAP_OUTDATED_BY_YOU=It's not possible to save your changes because map is out of date. Do you have multiple tabs opened ?. Refresh the page and try again.
 MINDMAP_LOCKED=Map is being edited by {0} <{1}>. Map  is opened in read only mode.