Cannot create an object of type 'Telerik.Web.UI.GridExcelExportFormat' from its string representation 'Xlsx' for the 'Format' property.

[Tanvir]

Cannot create an object of type 'Telerik.Web.UI.GridExcelExportFormat' from its string representation 'Xlsx' for the 'Format' property.

 <groupingsettings collapsealltooltip="Collapse all groups" />
Line 393:                <exportsettings exportonlydata="True">
Line 394:                    <Excel Format="Xlsx" />
Line 395:                </exportsettings>
Line 396:                <HeaderStyle BackColor="#614051" ForeColor="White" HorizontalAlign="Center" VerticalAlign="Middle" />

[Tanvir]

Firstly I run the application from the previous download that time it works perfectly. But now when I again downloaded It I just copy the file from bin35 but my system is an upgrade version so that error occur.  But when I copy .dll from bin45 at that time It works perfectly.

[Attila Antal]

That is correct Tanvir. The XLSX is only supported by .NET 4.0 and above, you will need the assemblies that target that version (.40 or .45)