When I try to add a RadWindow or other Telerik controls to my WPF application I get an error

[Corey]

An error occurred while running the wizard.

Error executing custom action Telerik.Windows.WPF.VSX.Actions.UpdateAppXamlFileAction: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
   at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
   at System.Collections.Generic.List`1.get_Item(Int32 index)
   at Telerik.Windows.WPF.VSX.Actions.UpdateAppXamlFileAction.TrySettingUserSelectedAssemblyReferences(IPropertyDataDictionary arguments)
   at Telerik.Windows.WPF.VSX.Actions.UpdateAppXamlFileAction.UpdateAppXaml(IPropertyDataDictionary arguments, IProjectWrap projectWrap)
   at Telerik.Windows.WPF.VSX.Actions.UpdateAppXamlFileAction.Execute(WizardContext wizardContext, IPropertyDataDictionary arguments, IProjectWrap projectWrap)
   at Telerik.VSX.Actions.ProjectActionBase.Execute(WizardContext wizardContext, IPropertyDataDictionary arguments)
   at Telerik.VSX.WizardEngine.Actions.ActionBase.Telerik.WizardFramework.IAction.Execute(IWizardContext wizardContext, IPropertyDataDictionary arguments)
   at Telerik.VSX.WizardEngine.ActionManager.ExecActions()

[Nikolay Mishev]

Hello Corey,

Thank you for contacting us.

I was able to reproduce the issue on my side and it looks like there is a bun in our Visual Studio Extensions.  I'm going to log it into our backlog, and it should be included in one of our future releases.

I was able to reproduce the issue with Telerik NoXaml project that does not have reference to a Telerik theme assembly. Please let me know if this is the case on your part. If yes you can use the Project Configuration Wizard to add a theme to your project and then check if the issue appears. Finally, you can check the Documentation on each control and add them manually until we fix the issue(Here is the Getting Started page for RadWindow).

As a token of gratitude for reporting this to us I have updated your Telerik Points.

I hope the provided information helps. Please do not hesitate to contact us if any other questions arise.

Regards,
Nikolay Mishev
Progress Telerik