Visual Studio 2013 Report Viewer - The report definition has an invalid target namespace

Question

I am getting the following error in my recently upgraded project:

The report definition has an invalid target namespace 'http://schemas.microsoft.com/sqlserver/reporting/2008/01/reportdefinition' which cannot be upgraded.

If I start fresh and add a new report, I still get this error. This is a local report running inside a Web Form. The website is compiled as .NET 4.5. I get this error whether I am using the ReportView version 9, 10, or 11.

Web Form contains:

<%@ Register Assembly="Microsoft.ReportViewer.WebForms, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Namespace="Microsoft.Reporting.WebForms" TagPrefix="rsweb" %>

Web.config contains:

<assemblies>
    <add assembly="Microsoft.ReportViewer.WebForms, Version=9.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
    <add assembly="Microsoft.ReportViewer.Common, Version=9.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
  </assemblies>

<httpHandlers>
      <add verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
    </httpHandlers>

Report tag in the .rdlc:

<Report xmlns="http://schemas.microsoft.com/sqlserver/reporting/2008/01/reportdefinition" xmlns:rd="http://schemas.microsoft.com/SQLServer/reporting/reportdesigner">

Answer 1

Here is a fix that I found that worked. Upgrade the report to be version 10 for the report viewer, so using all version 10 assemblies and references.

then in the web.config add the following to system.webServer:

<handlers>
      <add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" 
           type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
</handlers>

After doing this, my report worked.