I was recently working on a reporting web application that uses the Report Viewer ( ReportViewer ) control that ships with SQL Server Reporting Services (SSRS). The Report Viewer control was rendering perfectly when I was developing using Visual Studio 2008. The trouble started when I published the web application to an IIS 7.0 server. The Toolbar was completely broken and showed up something like this.
<rsweb:ReportViewer AsyncRendering="false" ID="reportViewer" Width="100%" Height="100%" runat="server" SizeToReportContent="True" > </rsweb:ReportViewer>
GET /Reserved.ReportViewerWebControl.axd?OpType=Resource&Version=9.0.30729.1&Name=Microsoft.Reporting.WebForms.Icons.NextPage.gif HTTP/1.1
GET /Reserved.ReportViewerWebControl.axd?OpType=Resource&Version=9.0.30729.1&Name=Microsoft.Reporting.WebForms.Icons.LastPage.gif HTTP/1.1
When you use the Report Viewer Control Visual Studio edits your web.config to map a Http Handler to respond to these requests.
<add path="Reserved.ReportViewerWebControl.axd" verb="*" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=126.96.36.199, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" validate="false"/>
The above entry tells ASP.NET that whenever a call is made to ReportViewerWebControl.axd use the Microsoft.Reporting.WebForms.HttpHandler assembly to execute it.
This mapping is very important because if you remove it the web server will return a 404 “File Not Found” error code because the ReportViewerWebControl.axd does not exist physically on the server.
Strangely when I checked the IIS 7.0 logs for the broken scenario I found that all requests for ReportViewerWebControl.axd had failed with a 404.
With IIS 7.0 there was an architectural change. There were changes to the web.config structure as well. The <httpHandlers> section that was under the <system.web> has now moved to <handlers> under <system.webServer>
Visual Studio had edited the web.config based on the IIS 6.0 model and had made an entry for the Http Handler under the <httpHandler> section. With IIS 7.0 this section is no longer read. So we need to make the proper entries for the Http Handler that handles the calls to ReportViewerWebControl.axd
<add name="ReportViewerWebControl" path="Reserved.ReportViewerWebControl.axd" verb="*" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=188.8.131.52, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
IIS 7.0 will now understand that whenever a call is made to ReportViewerWebControl.axd it needs to route it to the Http Handler Microsoft.Reporting.WebForms.HttpHandler
Cross posted from Vijay’s Blog ( http://blogs.msdn.com/vijaysk/archive/2009/01/14/report-viewer-toolbar-does-not-render-properly-on-iis-7-0.aspx )