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Failed to setup service when adding Report Viewer control on the page.


Product Progress® Telerik® Reporting
Report Viewer HTML5 ASP.NET WebForms ReportViewer
Project Type Web Site


Attempting to add a Report Viewer control on the design surface of a WebForm leads to an error being thrown.

For example, attempting to drag the HTML5 ASP.NET WebForms ReportViewer from the VS Toolbox onto a WebForm.aspx page in Design mode, will result in the described error.

Error Message

Failed to setup service.
System.InvalidCastException: Unable to cast COM object of type 'System.__ComObject' to class type 'Telerik.Reporting.Vs.Common.AssemblyReference'. Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.
   at Telerik.Reporting.Vs.Common.DTEReferences.WebSiteReferences.Contains(String assemblyName)
   at Telerik.Reporting.Vs.Common.DTEReferences.WebSiteReferences.Contains(AssemblyName assemblyName)
   at Telerik.ReportViewer.Html5.WebForms.Design.InitialConfigHelper.ConfigureReferences(DTEProject project)
   at Telerik.ReportViewer.Html5.WebForms.Design.InitialConfigHelper.ConfigureFirstTime(IServiceProvider serviceProvider)

Possible Cause

Web Site projects handle assembly references differently, which is the major reason Telerik Reporting not to provide design time support for Web Site projects.


The recommended approach is to use reports designed with the Standalone Report Designer, or reports from an external assembly referenced by the Web Site project. The Report Viewers have to be configured manually in Web Site projects:


The automatic upgrade feature is not designed to work with Web Site projects as well.

Web Site projects must be upgraded manually - Upgrading Telerik Reporting Projects.

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