Index: DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/IO/VersionInfo.cs
===================================================================
diff -u -r4539 -r6310
--- DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/IO/VersionInfo.cs	(.../VersionInfo.cs)	(revision 4539)
+++ DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/IO/VersionInfo.cs	(.../VersionInfo.cs)	(revision 6310)
@@ -32,7 +32,8 @@
     /// FileVersion 0 is for versions 18.1.3 and earlier.</summary>
     /// FileVersion 1 is for version 19.1.1.</summary>
     /// FileVersion 2 is for version 20.1.1. and up</summary>
-    public const int CurrentFileVersion = 2;
+    /// FileVersion 2 is for version 25.1.1. and up</summary>
+    public const int CurrentFileVersion = 3;
 
     //#Bka: added this field to be able to debug the de-serialization of the file version info.
     // I noticed that when the designresults are added to the serialization/de-serialization,
Index: DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/Translations.xml
===================================================================
diff -u -r6267 -r6310
--- DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/Translations.xml	(.../Translations.xml)	(revision 6267)
+++ DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/Translations.xml	(.../Translations.xml)	(revision 6310)
@@ -836,5 +836,8 @@
                  nl-NL="Geen gegevensbronnen gedefinieerd"/>
     <Translation ID="DataHasNotBeenImportedYet"
                  en-US="Data has not been imported yet"
-                 nl-NL="Gegevens zijn nog niet geïmporteerd"/>    
+                 nl-NL="Gegevens zijn nog niet geïmporteerd"/>
+    <Translation ID="CanNotReadOldFile" 
+                 en-US="You try to open an old file. That is not possible. Please make a new damx file based upon a defx file."
+                 nl-NL="U probeert een oud bestand te openen, dat is niet mogelijk. Maak een nieuw damx bestand op basis van een defx bestand."/>
 </Translations>
\ No newline at end of file
Index: DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamProject.cs
===================================================================
diff -u -r6295 -r6310
--- DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamProject.cs	(.../DamProject.cs)	(revision 6295)
+++ DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamProject.cs	(.../DamProject.cs)	(revision 6310)
@@ -297,7 +297,10 @@
             if (damProjectData != null)
             {
                 damProjectData.VersionInfo.InitVersionInfoAfterRead();
-                
+                if (damProjectData.VersionInfo.FileVersionAsRead < damProjectData.VersionInfo.FileVersion)
+                {
+                    throw new DamProjectException(LocalizationManager.GetTranslatedText(GetType(), "CanNotReadOldFile"));
+                }
                 string damProjectVersion = damProjectVersionXmlHandler.GetDamProjectVersion();
                 damProjectVersion = GetMainVersion(damProjectVersion);
                 if (damProjectVersion != null)