Hi Rohit,
I would suggest you to follow the approach provided in the online example below for uploading new image using RadAsyncUpload in RadGrid.
http://demos.telerik.com/aspnet-ajax/controls/examples/integration/gridandradasyncupload/defaultcs.aspx?product=grid
Give it a try and let me know if the presented error appear.
Regards,
Maria Ilieva
Telerik
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