The SqlReportViewer proxy handler needs to be registered into the web project. It is used to buffer the XAML results in streaming loading mode and compress the stream to be delivered to the Silverlight client, which will be further processed by the SqlReportViewer control.

Follow the steps below to register SqlReportViewer proxy handler in web project.

1. Open the Web.config file in the Silverlight web project.
2. Add a new entry for SqlReportViewer proxy in httpHandler node under configuration/system.web

<add verb="*" path="SQLReportViewerHandler.ashx" type="Intersoft.SqlReportViewer.Server.SqlReportViewerHandler, Intersoft.SqlReportViewer.Server" />

I'd like to recommend you to check the complete reference of how to configure SqlReportViewer for first time use in here.

Hope this help.

Where can I find the file SQLReportViewerHandler.ashx?

The SqlReportViewer proxy handler is included in Intersoft.SqlReportViewer.Server.dll assembly. The file can be found in "[Intersoft Solutions Installation folder]\ClientUI 10\Server\Intersoft.SqlReportViewer.Server.dll".