Workflow activities disappeared


I got a strange issue with a flowchart - out of a sudden, all the activities in a workflow I was working on, disappeared, along with the error message from the screenshot.

If I invoke this flowchart somewhere else, it still keeps its functionality, but I cannot edit anything in it (as the activities are hidden).

Any solution to this, guys? :slight_smile:

The detailed error message is below:

An internal error has occurred. It is recommended to restart UiPath Studio.

Error: System.ArgumentNullException: Value cannot be null.
Parameter name: key

  • at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)*
  • at System.Activities.Core.Presentation.FlowchartDesigner.SetFlowElementModelItem(UIElement view, ModelItem model)*
  • at System.Activities.Core.Presentation.FlowchartDesigner.ProcessAndGetModelView(ModelItem model)*
  • at System.Activities.Core.Presentation.FlowchartDesigner.AddFlowElementsToDesigner(IList`1 flowElementMICollection, Boolean addConnectorAfterLoaded)*
  • at System.Activities.Core.Presentation.FlowchartDesigner.PopulateFlowchartChildren()*
  • at System.Activities.Core.Presentation.FlowchartDesigner.OnFreeFormPanelLoaded(Object sender, RoutedEventArgs eventArgs)*
  • 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.RaiseEvent(RoutedEventArgs e)*
  • at System.Windows.BroadcastEventHelper.BroadcastEvent(DependencyObject root, RoutedEvent routedEvent)*
  • at System.Windows.BroadcastEventHelper.BroadcastLoadedEvent(Object root)*
  • at MS.Internal.LoadedOrUnloadedOperation.DoWork()*
  • at System.Windows.Media.MediaContext.FireLoadedPendingCallbacks()*
  • at System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()*
  • at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)*
  • at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)*
  • at System.Windows.Media.MediaContext.Resize(ICompositionTarget resizedCompositionTarget)*
  • at System.Windows.Interop.HwndTarget.OnResize()*
  • at System.Windows.Interop.HwndTarget.HandleMessage(WindowMessage msg, IntPtr wparam, IntPtr lparam)*
  • at System.Windows.Interop.HwndSource.HwndTargetFilterMessage(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*


Restart the UiPath Studio, clean the temp files from run command using - %temp%
Still facing same issue, restart your machine and check again.

I see this sometimes on mine. I would click retry later. Copy the file and place somewhere just in case. Then I would save, then restart. It’s never destroyed my data before so you should be good.

Happy Botting!

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Thank you for the help.
Unfortunately, none of these solved the issue…

kindly delete the project.json file and then open your .xaml file
Cheers @alin.mihalea