Got internal error when click on activity
18.3.1+Branch.master.Sha.4c05f670b311e90ee097c589605b399e9bee4874
An internal error has occurred. It is recommended to restart UiPath Studio.
Error: System.NullReferenceException: Object reference not set to an instance of an object.
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelProperty(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty, ModelProperty property)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelItem(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemModelItemViewModel.LoadChildren()
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddChild(TreeViewItemViewModel child, ModelProperty modelProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddChild(TreeViewItemViewModel parent, ModelItem item, Object value, Boolean duplicatedNodeVisible, String childNodePrefix, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelItemCollection(TreeViewItemViewModel parent, ModelItemCollection collection, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelProperty(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty, ModelProperty property)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelItem(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelProperty(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty, ModelProperty property)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelItem(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemModelItemViewModel.LoadChildren()
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddChild(TreeViewItemViewModel child, ModelProperty modelProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelProperty(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty, ModelProperty property)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddModelItem(TreeViewItemViewModel parent, ModelItem item, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemModelItemViewModel.LoadChildren()
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddChild(TreeViewItemViewModel child, ModelProperty modelProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.AddChild(TreeViewItemViewModel parent, ModelItem item, Object value, Boolean duplicatedNodeVisible, String childNodePrefix, ModelProperty trackingProperty)
at System.Activities.Presentation.View.TreeView.TreeViewItemModelPropertyViewModel.LoadChildren()
at System.Activities.Presentation.View.TreeView.TreeViewItemViewModel.set_IsExpanded(Boolean value)
at System.Activities.Presentation.View.TreeView.DesignerTreeAutoExpandHelper.Expand(TreeViewItemModelItemViewModel rootTreeViewItem, ModelItem modelItemToExpandTo)
at System.Activities.Presentation.View.TreeView.DesignerTreeView.ModelItemSelectionChanged(Selection selection)
at System.Activities.Presentation.ContextItemManager.SubscribeProxy`1.SubscribeContext(ContextItem item)
at System.Activities.Presentation.SubscribeContextCallback.Invoke(ContextItem item)
at System.Activities.Presentation.EditingContext.DefaultContextItemManager.OnItemChanged(ContextItem item)
at System.Activities.Presentation.EditingContext.DefaultContextItemManager.SetValue(ContextItem value)
at System.Activities.Presentation.View.Selection.SelectOnly(EditingContext context, ModelItem itemToSelect)
at System.Activities.Presentation.WorkflowViewElement.OnMouseDown(MouseButtonEventArgs e)
at System.Windows.UIElement.OnMouseDownThunk(Object sender, MouseButtonEventArgs e)
at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler), HResult -2147467261