'RSClientController' is undefined
Try this , <system.webServer> <handlers> <add name="Reserved.ReportViewerWebControl.axd" path="Reserved.ReportViewerWebControl.axd" verb="*" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" resourceType="Unspecified" preCondition="integratedMode" /> </handlers> </system.webServer>