I installed the new version and when I try to edit a flow I get this error

and I can't edit, why?
error destails:
Messaggio = Riferimento a un oggetto non impostato su un'istanza di oggetto.
Errore = System.NullReferenceException
Full-text = System.NullReferenceException: Riferimento a un oggetto non impostato su un'istanza di oggetto.
in System.Windows.Automation.Peers.AutomationPeer.EnsureChildren()
in System.Windows.Automation.Peers.AutomationPeer.UpdateChildrenInternal(Int32 invalidateLimit)
in System.Windows.Automation.Peers.ItemsControlAutomationPeer.UpdateChildren()
in System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
in System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
in System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
in System.Windows.ContextLayoutManager.fireAutomationEvents()
in System.Windows.ContextLayoutManager.UpdateLayout()
in System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)
in System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
in System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
in System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
in System.Windows.Interop.HwndTarget.OnResize()
in System.Windows.Interop.HwndTarget.HandleMessage(WindowMessage msg, IntPtr wparam, IntPtr lparam)
in System.Windows.Interop.HwndSource.HwndTargetFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
in MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
in MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
in System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
in System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)