When I install the Microsoft Report Viewer 2010 Redistributable Package on my server it shows up in the gac here: C:\WINDOWS\assembly\gac\ but not in the 4.0 version of the gac here: C:\WINDOWS\Microsoft.NET\assembly\GAC_MSIL\ Why is this? My application (which is written in .net 2010) is failing because it can't find Microsoft.ReportViewer.WinForms -- Anthony

It seems I sort of answered my own question. It appears that even though I'm using .Net 2010 reportviewer for 2010 is still a .Net 3.5 object. I did a iisreset and my app started working. Though this begs the question, why is there a reportviewer on my development machine in the 4.0 gac folder? Why do the versions not match?

Hi Anthony.2, The Report Viewer control is the version of .NET framework regardless. In order to check if it is installed to GAC correctly, please go to C:\Windows\assembly, and check if following assemblies is installed with version 10.0.0.0 Microsoft.ReportViewer.WebForms Microsoft.ReportViewer.WebForms WinForms Microsoft.ReportViewer.ProcessingObjectModel Microsoft.ReportViewer.DataVisualization Microsoft.ReportViewer.Common The assemblies Microsoft.ReportViewer.Design and Microsoft.ReportViewer.WebDesign in C:\WINDOWS\Microsoft.NET\assembly\GAC_MSIL\ is used fo design reports in .NET 4.0 object only. It is not the assemblies for Report Viewer control. It comes with Visual Studio 2010. If you have any more questions, please feel free to ask. Thanks, Jin ChenJin Chen - MSFT