- Open Internet Information Services (IIS) Manager and select your Web application.
- Under IIS area, double-click on Handler Mappings icon.
- At the Action pane on your right, click on Add Managed Handler.
- At the Add Managed Handler dialog, enter the following:
Request path: Reserved.ReportViewerWebControl.axd
- Click OK.
Reserved-ReportViewerWebControl-axd handler is now added to your Handler Mappings list. Notice that the following line has also been added to your Web.config file under the system.webserver’s handler section:
<add name=”Reserved-ReportViewerWebControl-axd” path=”Reserved.ReportViewerWebControl.axd”
verb=”*” type=”Microsoft.Reporting.WebForms.HttpHandler” resourceType=”Unspecified”
Found at: http://otkfounder.blogspot.com/2007/11/solving-reportviewer-rendering-issue-on.html