Index: Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuBuilder.cs
===================================================================
diff -u -r836d03bd77cc7848d686b59c61fd63ef711c7b32 -red4051ed5a4979fcc002c2d2100ac1c80007dd1b
--- Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuBuilder.cs	(.../RingtoetsContextMenuBuilder.cs)	(revision 836d03bd77cc7848d686b59c61fd63ef711c7b32)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuBuilder.cs	(.../RingtoetsContextMenuBuilder.cs)	(revision ed4051ed5a4979fcc002c2d2100ac1c80007dd1b)
@@ -133,6 +133,8 @@
         /// <typeparam name="TCalculationItemContext">The type of the calculation item context.</typeparam>
         /// <param name="calculationItem">The calculation item to duplicate.</param>
         /// <param name="calculationItemContext">The calculation item context belonging to the calculation item.</param>
+        /// <exception cref="ArgumentException">Thrown when the parent calculation group of
+        /// <paramref name="calculationItem"/> equals <c>null</c>.</exception>
         /// <returns>The <see cref="RingtoetsContextMenuBuilder"/> itself.</returns>
         public RingtoetsContextMenuBuilder AddDuplicateCalculationItem<TCalculationItem, TCalculationItemContext>(
             TCalculationItem calculationItem,
Index: Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuItemFactory.cs
===================================================================
diff -u -r836d03bd77cc7848d686b59c61fd63ef711c7b32 -red4051ed5a4979fcc002c2d2100ac1c80007dd1b
--- Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuItemFactory.cs	(.../RingtoetsContextMenuItemFactory.cs)	(revision 836d03bd77cc7848d686b59c61fd63ef711c7b32)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuItemFactory.cs	(.../RingtoetsContextMenuItemFactory.cs)	(revision ed4051ed5a4979fcc002c2d2100ac1c80007dd1b)
@@ -21,6 +21,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Drawing;
 using System.Linq;
 using System.Windows.Forms;
@@ -180,13 +181,20 @@
         /// <typeparam name="TCalculationItemContext">The type of the calculation item context.</typeparam>
         /// <param name="calculationItem">The calculation item to duplicate.</param>
         /// <param name="calculationItemContext">The calculation item context belonging to the calculation item.</param>
+        /// <exception cref="ArgumentException">Thrown when the parent calculation group of
+        /// <paramref name="calculationItem"/> equals <c>null</c>.</exception>
         /// <returns>The created <see cref="StrictContextMenuItem"/>.</returns>
         public static StrictContextMenuItem CreateDuplicateCalculationItem<TCalculationItem, TCalculationItemContext>(
             TCalculationItem calculationItem,
             TCalculationItemContext calculationItemContext)
             where TCalculationItemContext : ICalculationContext<TCalculationItem, IFailureMechanism>
             where TCalculationItem : ICalculationBase
         {
+            if (calculationItemContext.Parent == null)
+            {
+                throw new ArgumentException($"{nameof(calculationItemContext.Parent)} should be set.");
+            }
+
             return new StrictContextMenuItem(
                 Resources.Duplicate,
                 Resources.Duplicate_ToolTip,
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/TreeNodeInfos/RingtoetsContextMenuItemFactoryTest.cs
===================================================================
diff -u -r836d03bd77cc7848d686b59c61fd63ef711c7b32 -red4051ed5a4979fcc002c2d2100ac1c80007dd1b
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/TreeNodeInfos/RingtoetsContextMenuItemFactoryTest.cs	(.../RingtoetsContextMenuItemFactoryTest.cs)	(revision 836d03bd77cc7848d686b59c61fd63ef711c7b32)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/TreeNodeInfos/RingtoetsContextMenuItemFactoryTest.cs	(.../RingtoetsContextMenuItemFactoryTest.cs)	(revision ed4051ed5a4979fcc002c2d2100ac1c80007dd1b)
@@ -651,12 +651,13 @@
         }
 
         [Test]
-        public void CreateDuplicateCalculationItem_Always_CreatesDecoratedAndEnabledItem()
+        public void CreateDuplicateCalculationItem_CalculationItemWithParent_CreatesDecoratedAndEnabledItem()
         {
             // Setup
             var mocks = new MockRepository();
             var calculationItem = mocks.Stub<ICalculationBase>();
             var calculationItemContext = mocks.Stub<ICalculationContext<ICalculationBase, IFailureMechanism>>();
+            calculationItemContext.Stub(ic => ic.Parent).Return(new CalculationGroup());
             mocks.ReplayAll();
 
             // Call
@@ -672,6 +673,25 @@
         }
 
         [Test]
+        public void CreateDuplicateCalculationItem_CalculationItemWithoutParent_ThrowsArgumentException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var calculationItem = mocks.Stub<ICalculationBase>();
+            var calculationItemContext = mocks.Stub<ICalculationContext<ICalculationBase, IFailureMechanism>>();
+            mocks.ReplayAll();
+
+            // Call
+            TestDelegate call = () => RingtoetsContextMenuItemFactory.CreateDuplicateCalculationItem(calculationItem, calculationItemContext);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentException>(call);
+            Assert.AreEqual($"{nameof(calculationItemContext.Parent)} should be set.", exception.Message);
+
+            mocks.VerifyAll();
+        }
+
+        [Test]
         [TestCaseSource(nameof(CalculationGroupConfigurations))]
         public void CreateDuplicateCalculationItem_PerformClickOnCreatedItem_DuplicatesCalculationItemWithExpectedNameAndPosition(ICalculationBase calculationItem,
                                                                                                                                   CalculationGroup calculationGroup,