Index: DamClients/DamUI/trunk/src/Dam/Deltares.Dam.BenchmarkTests/DamCalculationBenchmarkTest.cs
===================================================================
diff -u -r4918 -r4969
--- DamClients/DamUI/trunk/src/Dam/Deltares.Dam.BenchmarkTests/DamCalculationBenchmarkTest.cs	(.../DamCalculationBenchmarkTest.cs)	(revision 4918)
+++ DamClients/DamUI/trunk/src/Dam/Deltares.Dam.BenchmarkTests/DamCalculationBenchmarkTest.cs	(.../DamCalculationBenchmarkTest.cs)	(revision 4969)
@@ -236,8 +236,8 @@
     [Test]
     [Category("Slow")]
     [TestCase(1)]
-    [TestCase(5)]
-    [TestCase(10)]
+    // [TestCase(5)]
+    // [TestCase(10)]
     public void Dijkring13NormalStabilityCalculationMultiCoreForMultiLocations(int maxCores)
     {
         const string cDikeFolder = @"..\..\..\..\..\data\benchmarks\Opdrijfberekeningen\Dijkring13-Sec1\DatabronbestandMulti.damx";
Index: DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamEngineIo/FillXmlInputFromDamUi.cs
===================================================================
diff -u -r4938 -r4969
--- DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamEngineIo/FillXmlInputFromDamUi.cs	(.../FillXmlInputFromDamUi.cs)	(revision 4938)
+++ DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamEngineIo/FillXmlInputFromDamUi.cs	(.../FillXmlInputFromDamUi.cs)	(revision 4969)
@@ -33,6 +33,7 @@
 using Deltares.Geotechnics.Soils;
 using Deltares.Geotechnics.SurfaceLines;
 using Deltares.Standard.Logging;
+using Deltares.Standard.Specifications;
 using Sensor = Deltares.Dam.Data.Sensors.Sensor;
 using SensorLocation = Deltares.DamEngine.Io.XmlInput.SensorLocation;
 using Soil = Deltares.Geotechnics.Soils.Soil;
@@ -366,6 +367,10 @@
             throw new ArgumentException(Resources.DikeShouldContainExactly1Dike);
         }
 
+        ThrowHelper.ThrowWhenConditionIsTrue<ValidationException>(
+            "Multicore is currently not supported. Change number of cores to 1 in Tools menu.", 
+            () => damProjectData.MaxCalculationCores > 1);
+
         Dike dike = damProjectData.WaterBoard.Dikes[0];
         ThrowHelper.ThrowIfArgumentNull(dike.Locations, nameof(dike.Locations), StringResourceNames.NoLocationsDefined);
         // Following situation should never occur in the UI. Tested because of the check on RiverLevelLow in the code below