Upgrading Web Application Projects to VS 2010

A number of people have posted questions about upgrading their VS 2008 web applications using the ReportViewer control to VS 2010.  The upgrade process is not automatic.  Before I get into the steps required to upgrade your applications to the VS 2010 ReportViewer, I’d like to take a moment to explain why this upgrade process is not automatic.

The VS 2008 ReportViewer can be used in the VS 2010 shell.  While you won’t get the design time experience associated with the 2008 viewer, it will function correctly at runtime.  Certainly, we want everyone to upgrade to the new version, but there are a few reasons you might not want to, and therefore why we don’t upgrade everything automatically:

  • Using the VS 2010 ASP.Net ReportViewer requires ASP.Net AJAX.  While this has not been an issue for most people, it is a new requirement and requires some changes to your ASP.Net pages.
  • The VS 2010 ReportViewer will not work against a SQL 2005 report server in server mode.  If you plan to connect to a SQL 2005 report server, you will need to stay on the VS 2008 version.
  • There are a few API changes that break backwards compatibility in the strict sense.  In response to customer feedback, some methods changed from a return value of void to something more useful.  These changes don’t require you to change your code, but they do require a recompilation.  Assembly version redirection won’t work.

After you load your web application in VS 2010, you will need to perform the following manual steps to get your application back to a fully working state:

  1. In the assembly references section of the solution explorer, remove any references to 9.0 ReportViewer assemblies and add their 10.0 equivalent.  Depending on the versions of the ReportViewer you have installed on your development machine, this may have been done for you.
  2. In the web.config file, locate all references to the ReportViewer assembly and replace the version string with  The public key token did not change in 10.0.  In a typical web.config file, there are four references to the report viewer:
    1. A reference to Microsoft.ReportViewer.WebForms in the system.web/compilation/assemblies section
    2. A reference to Microsoft.ReportViewer.Common in the system.web/compilation/assemblies section
    3. A reference to the RdlBuildProvider in system.web/compilation/buildProviders section
    4. A reference to the HTTP handler in the system.web/httpHandlers section.  Depending on the version of IIS that you are targeting, a similar reference may also be in the system.webServer/handlers section.
  3. In each ASPX file that references the ReportViewer control, a register tag was added when you first inserted a ReportViewer control on the page.  This reference also needs to be updated from to
  4. If you did not already have an ASP.Net AJAX ScriptManager on the page, you will need to add one to the top of the page.  It is located in the AJAX Extensions section of the Toolbox.