Resolution:
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.axdType: Microsoft.Reporting.WebForms.HttpHandlerName: 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:
For more information, see
http://forums.asp.net/p/1360494/2814290.aspx#2814290