"System.ArgumentException: An item with the same key has already been added." exception is thrown.
When xlsx/docx document is imported, and its main story is with non-default name ('workbook. xml'/'document.xml'), e.g. workbook2.xml/document2.xml, NullReferenceException is thrown and the document is not imported. Note: Such documents are usually produced after conversion from a template dotx/xlsm.
Currently EULA requires Telerik assemblies to be protected against unauthorized redistribution, by following specific guidelines for the different types of technology: - for WPF: https://docs.telerik.com/devtools/wpf/installation-and-deployment/deploying-telerik-ui/protecting-telerik-assembly - for ASP.NET AJAX: https://docs.telerik.com/devtools/aspnet-ajax/deployment/protecting-the-telerik-asp.net-ajax-assembly - for WinForms: https://docs.telerik.com/devtools/winforms/installation-deployment-and-distribution/redistributing-telerik-ui-for-winforms When the guidelines for WinForms or AJAX are followed (namely the call to ValidatePassPhrase() is uncommented in AssemblyProtection.IsValid() method, the following license message is added to the generated documents: "This document was generated by a copy of Telerik Document Processing licensed for use only by '<MyApp>'." Workaround: Set the application name as resource in the Application.Current, using the following code: new System.Windows.Application(); System.Windows.Application.Current.Resources.Add("Telerik.Windows.Controls.Key", "MyApp"); where 'MyApp' should be replaces with the actual application name. References to PresentationFramework and WindowsBase .NET Framework assemblies should be added in order this to work.