When my application runs in full trust permissions set, the following error is thrown if I have used the Telerik.Reporting.OpenXmlRendering NuGet package and try exporting to any of the OpenXML formats :
ERROR: Attempt by security transparent method 'Telerik.Reporting.OpenXmlRendering.Spreadsheet.Workbook..ctor()' to access security critical method 'DocumentFormat.OpenXml.Packaging.SpreadsheetDocument.Create(System.IO.Stream, DocumentFormat.OpenXml.SpreadsheetDocumentType)' failed.