diff --git a/src/DynamoCoreWpf/UI/GuidedTour/GuidesValidationMethods.cs b/src/DynamoCoreWpf/UI/GuidedTour/GuidesValidationMethods.cs
index 9e4fde446a3..d776cb42f20 100644
--- a/src/DynamoCoreWpf/UI/GuidedTour/GuidesValidationMethods.cs
+++ b/src/DynamoCoreWpf/UI/GuidedTour/GuidesValidationMethods.cs
@@ -697,10 +697,13 @@ internal static void HighlightPort(Step stepInfo, StepUIAutomation uiAutomationD
             //Once we have the ItemsControl we get the ContentPresenter
             var inputViewModel = inPorts.FirstOrDefault(x => x.PortName == (string)uiAutomationData.Parameters[3]);
             var dependencyObject = itemsControlPort.ItemContainerGenerator.ContainerFromItem(inputViewModel);
-
-
             Grid mainGrid = dependencyObject.ChildOfType<Grid>();
 
+            // ContainerFromItem returns null when the ItemsControl hasn't generated the
+            // container yet (e.g. timing race during guided-tour initialization). Skip the
+            // highlight rather than crash — the tour can continue without it.
+            if (mainGrid == null) return;
+
             if (enableFunction)
             {
                 //Creates the highlight rectangle so it can be added and shown over the port