Ran into this issue the other day at work. We were developing some reporting services reports for a client and viewing them through a report viewer control in the intranet site we were developing.

The reports ran fine in the development environment but as soon as it was published to testing the reports behaved strangely. The test box was a Windows 2008 Server Standard Edition with IIS installed and .NET 3.5 SP1.

The reports page was reporting a 404 on the following resource “Reserved.ReportViewerWebControl.axd”

This handler was definitely present in the web.config file:

I did the following to resolve this issue.

  1. Install Report Viewer 2008 Redist + SP1
  2. In IIS 7 | Handler Mappings
  1. Under Actions | Add Managed Handler…

    1. Request path: Reserved.ReportViewerWebControl.axd
    2. Type: Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
    3. Name: Reserved-ReportViewerWebControl-axd

  2. Click OK
Now the reports load up fine.