System.Exception: Input string was not in a correct format

Hello everyone,

currently I am testing the new activity packages in our projects and I am encountering an error at a very simple activity: The Comment-Activity.

Studio shows me the following Exception:

Fehler: System.Exception: Die Eingabezeichenfolge hat das falsche Format.
bei System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
bei System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
bei System.Convert.ToInt32(String value)
bei Markdown.Xaml.Markdown.ListEvaluator(Match match)
bei Markdown.Xaml.Markdown.d__831.MoveNext() bei Markdown.Xaml.Markdown.<Evaluate>d__831.MoveNext()
bei Markdown.Xaml.Markdown.d__831.MoveNext() bei Markdown.Xaml.Markdown.<Evaluate>d__831.MoveNext()
bei Markdown.Xaml.Markdown.Create[TResult,TContent](IEnumerable`1 content)
bei Markdown.Xaml.Markdown.Transform(String text)
bei Markdown.Xaml.TextToFlowDocumentConverter.Convert(Object value, Type targetType, Object parameter, CultureInfo culture)
bei System.Windows.Data.BindingExpression.TransferValue(Object newValue, Boolean isASubPropertyChange)
bei System.Windows.Data.BindingExpression.Activate(Object item)
bei System.Windows.Data.BindingExpression.AttachToContext(AttachAttempt attempt)
bei System.Windows.Data.BindingExpression.MS.Internal.Data.IDataBindEngineClient.AttachToContext(Boolean lastChance)
bei MS.Internal.Data.DataBindEngine.Task.Run(Boolean lastChance)
bei MS.Internal.Data.DataBindEngine.Run(Object arg)
bei MS.Internal.Data.DataBindEngine.OnLayoutUpdated(Object sender, EventArgs e)
bei System.Windows.ContextLayoutManager.fireLayoutUpdateEvent()
bei System.Windows.ContextLayoutManager.UpdateLayout()
bei System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)
bei System.Windows.Media.MediaContext.InvokeOnRenderCallback.DoWork()
bei System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
bei System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
bei System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
bei System.Windows.Media.MediaContext.Resize(ICompositionTarget resizedCompositionTarget)
bei System.Windows.Interop.HwndTarget.OnResize()
bei System.Windows.Interop.HwndTarget.HandleMessage(WindowMessage msg, IntPtr wparam, IntPtr lparam)
bei System.Windows.Interop.HwndSource.HwndTargetFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
bei MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
bei MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
bei System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler), HResult -2146233033

In the comment-activity I use the following String:

UiPath kann deutsche Datumsangaben nicht 1:1 casten, da es das US-Format erwartet (MM/dd/yyyy). Dieser Workflow nimmt den Entwickler die zwei Extraschritte ab und gibt ein Datetime-Object zurück.

Das Datetime-Object kann zum Vergleichen von Datetimes genutzt werden.

Erlaubte DE-Formate:

  • dd.MM.yyyy
  • dd.MM.yyyy HH:00

In our project we used the activity package:
UiPath.System.Activities 21.10.2

I upgraded to the activity package version:

The activity is used in a large amount of workflows and test cases (>400 XAMLs) and the exception denies a proper view in the design panel:


My workaround is to downgrade the activity package but it’s not a final solution. Is it a known error? Will there be a fix?


Hi @WalterB

Could you please share your Studio version and whether the project is a legacy or a windows one?

Hi Maciej,
Studio Version 22.10.3 And Windows - Legacy

We can’t use Windows because of known issues (Studio Project Validation Operations Take So Long)

I tried reproducing this issue on the Studio 22.10.4 and couldn’t get it to reproduce:

Two things that were different to your environment:

  • my Studio was in English
  • my Studio was one patch higher that your version 22.10.3

Therefore, could you please try on an English language, and if possible, please update to the latest Studio patch (currently 22.10.5).