Note: This issue should be resolved by converting VS 2008 (SSRS 2005) RDLCs to VS 2010 (SSRS 2008) RDLCs and adding Microsoft.ReportViewer.WebForms.dll Version 10 reference to your .NET Framework 3.5 project’s references instead of Version 9 Thanks to the Framework Multi-Targeting new feature of Visual Studio 2010 which enables .NET developers to develop .NET applications… Continue reading Visual Studio 2010 Report Designer doesn’t support SSRS 2005 format