Index: Riskeer/Common/src/Riskeer.Common.Forms/Helpers/TargetProbabilityCalculationsDisplayNameHelper.cs
===================================================================
diff -u -rd9119b8f4a74fb2a6f3ececeaea94f0e58513c52 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/Helpers/TargetProbabilityCalculationsDisplayNameHelper.cs	(.../TargetProbabilityCalculationsDisplayNameHelper.cs)	(revision d9119b8f4a74fb2a6f3ececeaea94f0e58513c52)
+++ Riskeer/Common/src/Riskeer.Common.Forms/Helpers/TargetProbabilityCalculationsDisplayNameHelper.cs	(.../TargetProbabilityCalculationsDisplayNameHelper.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -91,6 +91,7 @@
         /// <exception cref="ArgumentNullException">Thrown when any input parameter is <c>null</c>.</exception>
         /// <exception cref="InvalidOperationException">Thrown when <paramref name="calculations"/> is not part of <paramref name="allCalculations"/>.</exception>
         public static string GetUniqueDisplayNameForCalculations<T>(T calculations, IEnumerable<T> allCalculations, Func<T, double> getTargetProbabilityFunc)
+            where T : class
         {
             if (calculations == null)
             {
Index: Riskeer/Common/src/Riskeer.Common.Forms/Observers/CalculatableFailureMechanismResultObserver.cs
===================================================================
diff -u -rd9119b8f4a74fb2a6f3ececeaea94f0e58513c52 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/Observers/CalculatableFailureMechanismResultObserver.cs	(.../CalculatableFailureMechanismResultObserver.cs)	(revision d9119b8f4a74fb2a6f3ececeaea94f0e58513c52)
+++ Riskeer/Common/src/Riskeer.Common.Forms/Observers/CalculatableFailureMechanismResultObserver.cs	(.../CalculatableFailureMechanismResultObserver.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -35,7 +35,7 @@
     /// <typeparam name="TCalculation">The type of the calculations in the <typeparamref name="TFailureMechanism"/>.</typeparam>
     public class CalculatableFailureMechanismResultObserver<TFailureMechanism, TSectionResult, TCalculation>
         : FailureMechanismResultObserver<TFailureMechanism, TSectionResult>
-        where TFailureMechanism : IFailureMechanism, IFailureMechanism<TSectionResult>, ICalculatableFailureMechanism
+        where TFailureMechanism : class, IFailureMechanism, IFailureMechanism<TSectionResult>, ICalculatableFailureMechanism
         where TSectionResult : FailureMechanismSectionResult
         where TCalculation : ICalculation<ICalculationInput>
     {
Index: Riskeer/Common/src/Riskeer.Common.Forms/Observers/FailureMechanismResultObserver.cs
===================================================================
diff -u -rd9119b8f4a74fb2a6f3ececeaea94f0e58513c52 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/Observers/FailureMechanismResultObserver.cs	(.../FailureMechanismResultObserver.cs)	(revision d9119b8f4a74fb2a6f3ececeaea94f0e58513c52)
+++ Riskeer/Common/src/Riskeer.Common.Forms/Observers/FailureMechanismResultObserver.cs	(.../FailureMechanismResultObserver.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -32,7 +32,7 @@
     /// <typeparam name="TFailureMechanism">The type of the failure mechanism to observe.</typeparam>
     /// <typeparam name="TSectionResult">The type of the section results in the failure mechanism.</typeparam>
     public class FailureMechanismResultObserver<TFailureMechanism, TSectionResult> : Observable, IDisposable
-        where TFailureMechanism : IFailureMechanism<TSectionResult>
+        where TFailureMechanism : class, IFailureMechanism<TSectionResult>
         where TSectionResult : FailureMechanismSectionResult
     {
         private readonly Observer failureMechanismObserver;
Index: Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/FailureMechanismItemContextBase.cs
===================================================================
diff -u -r5a3413865fad43cc268394aeb16a3ea69ed8e6e4 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/FailureMechanismItemContextBase.cs	(.../FailureMechanismItemContextBase.cs)	(revision 5a3413865fad43cc268394aeb16a3ea69ed8e6e4)
+++ Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/FailureMechanismItemContextBase.cs	(.../FailureMechanismItemContextBase.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -34,7 +34,7 @@
     /// <typeparam name="TFailureMechanism">The type of the failure mechanism which the context belongs to.</typeparam>
     public abstract class FailureMechanismItemContextBase<TData, TFailureMechanism> : ObservableWrappedObjectContextBase<TData>
         where TData : class, IObservable
-        where TFailureMechanism : IFailureMechanism
+        where TFailureMechanism : class, IFailureMechanism
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="FailureMechanismItemContextBase{TData,TFailureMechanism}"/> class.
Index: Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/InputContextBase.cs
===================================================================
diff -u -r5a3413865fad43cc268394aeb16a3ea69ed8e6e4 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/InputContextBase.cs	(.../InputContextBase.cs)	(revision 5a3413865fad43cc268394aeb16a3ea69ed8e6e4)
+++ Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/InputContextBase.cs	(.../InputContextBase.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -34,8 +34,8 @@
     /// <typeparam name="TFailureMechanism">The type of the failure mechanism which the context belongs to.</typeparam>
     public abstract class InputContextBase<TInput, TCalculation, TFailureMechanism> : FailureMechanismItemContextBase<TInput, TFailureMechanism>
         where TInput : class, ICalculationInput
-        where TCalculation : ICalculation
-        where TFailureMechanism : IFailureMechanism
+        where TCalculation : class, ICalculation
+        where TFailureMechanism : class, IFailureMechanism
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="InputContextBase{TData,TCalculation,TFailureMechanism}"/> class.
Index: Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/StructuresCalculationScenarioContext.cs
===================================================================
diff -u -rd9119b8f4a74fb2a6f3ececeaea94f0e58513c52 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/StructuresCalculationScenarioContext.cs	(.../StructuresCalculationScenarioContext.cs)	(revision d9119b8f4a74fb2a6f3ececeaea94f0e58513c52)
+++ Riskeer/Common/src/Riskeer.Common.Forms/PresentationObjects/StructuresCalculationScenarioContext.cs	(.../StructuresCalculationScenarioContext.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -36,7 +36,7 @@
     public class StructuresCalculationScenarioContext<TInput, TFailureMechanism> : FailureMechanismItemContextBase<StructuresCalculationScenario<TInput>, TFailureMechanism>,
                                                                                    ICalculationContext<StructuresCalculationScenario<TInput>, TFailureMechanism>
         where TInput : IStructuresCalculationInput, new()
-        where TFailureMechanism : ICalculatableFailureMechanism
+        where TFailureMechanism : class, ICalculatableFailureMechanism
     {
         /// <summary>
         /// Creates a new instance of <see cref="StructuresCalculationScenarioContext{TInput, TFailureMechanism}"/>.
Index: Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/StructuresInputBaseProperties.cs
===================================================================
diff -u -rd9119b8f4a74fb2a6f3ececeaea94f0e58513c52 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/StructuresInputBaseProperties.cs	(.../StructuresInputBaseProperties.cs)	(revision d9119b8f4a74fb2a6f3ececeaea94f0e58513c52)
+++ Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/StructuresInputBaseProperties.cs	(.../StructuresInputBaseProperties.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -57,8 +57,8 @@
         IHasForeshoreProfileProperty
         where TStructure : StructureBase
         where TStructureInput : StructuresInputBase<TStructure>
-        where TCalculation : ICalculation
-        where TFailureMechanism : IFailureMechanism
+        where TCalculation : class, ICalculation
+        where TFailureMechanism : class, IFailureMechanism
     {
         private readonly Dictionary<string, int> propertyIndexLookup;
 
Index: Riskeer/Common/test/Riskeer.Common.Forms.Test/PresentationObjects/FailureMechanismItemContextBaseTest.cs
===================================================================
diff -u -r5a3413865fad43cc268394aeb16a3ea69ed8e6e4 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/test/Riskeer.Common.Forms.Test/PresentationObjects/FailureMechanismItemContextBaseTest.cs	(.../FailureMechanismItemContextBaseTest.cs)	(revision 5a3413865fad43cc268394aeb16a3ea69ed8e6e4)
+++ Riskeer/Common/test/Riskeer.Common.Forms.Test/PresentationObjects/FailureMechanismItemContextBaseTest.cs	(.../FailureMechanismItemContextBaseTest.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -92,7 +92,7 @@
 
         private class SimpleFailureMechanismItemContext<TData, TFailureMechanism> : FailureMechanismItemContextBase<TData, TFailureMechanism>
             where TData : class, IObservable
-            where TFailureMechanism : IFailureMechanism
+            where TFailureMechanism : class, IFailureMechanism
         {
             public SimpleFailureMechanismItemContext(TData target, TFailureMechanism failureMechanism, IAssessmentSection assessmentSection)
                 : base(target, failureMechanism, assessmentSection) {}
Index: Riskeer/Common/test/Riskeer.Common.Forms.Test/PresentationObjects/InputContextBaseTest.cs
===================================================================
diff -u -r5a3413865fad43cc268394aeb16a3ea69ed8e6e4 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Common/test/Riskeer.Common.Forms.Test/PresentationObjects/InputContextBaseTest.cs	(.../InputContextBaseTest.cs)	(revision 5a3413865fad43cc268394aeb16a3ea69ed8e6e4)
+++ Riskeer/Common/test/Riskeer.Common.Forms.Test/PresentationObjects/InputContextBaseTest.cs	(.../InputContextBaseTest.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -76,8 +76,8 @@
 
         private class SimpleInputContext<TInput, TCalculation, TFailureMechanism> : InputContextBase<TInput, TCalculation, TFailureMechanism>
             where TInput : class, ICalculationInput
-            where TCalculation : ICalculation
-            where TFailureMechanism : IFailureMechanism
+            where TCalculation : class, ICalculation
+            where TFailureMechanism : class, IFailureMechanism
         {
             public SimpleInputContext(TInput input, TCalculation calculation, TFailureMechanism failureMechanism, IAssessmentSection assessmentSection)
                 : base(input, calculation, failureMechanism, assessmentSection) {}
Index: Riskeer/Integration/src/Riskeer.Integration.Forms/Observers/AssessmentSectionResultObserver.cs
===================================================================
diff -u -rd9119b8f4a74fb2a6f3ececeaea94f0e58513c52 -r4e485c84fa396729d920ec90af4274ab91991a89
--- Riskeer/Integration/src/Riskeer.Integration.Forms/Observers/AssessmentSectionResultObserver.cs	(.../AssessmentSectionResultObserver.cs)	(revision d9119b8f4a74fb2a6f3ececeaea94f0e58513c52)
+++ Riskeer/Integration/src/Riskeer.Integration.Forms/Observers/AssessmentSectionResultObserver.cs	(.../AssessmentSectionResultObserver.cs)	(revision 4e485c84fa396729d920ec90af4274ab91991a89)
@@ -226,7 +226,7 @@
         }
 
         private Observer CreateCalculatableFailureMechanismObserver<TFailureMechanism, TSectionResult, TCalculation>(TFailureMechanism failureMechanism)
-            where TFailureMechanism : IFailureMechanism, IFailureMechanism<TSectionResult>, ICalculatableFailureMechanism
+            where TFailureMechanism : class, IFailureMechanism, IFailureMechanism<TSectionResult>, ICalculatableFailureMechanism
             where TSectionResult : FailureMechanismSectionResult
             where TCalculation : ICalculation<ICalculationInput>
         {
@@ -238,7 +238,7 @@
         }
 
         private Observer CreateFailureMechanismObserver<TFailureMechanism, TSectionResult>(TFailureMechanism failureMechanism)
-            where TFailureMechanism : IFailureMechanism<TSectionResult>
+            where TFailureMechanism : class, IFailureMechanism<TSectionResult>
             where TSectionResult : FailureMechanismSectionResult
         {
             return new Observer(NotifyObservers)