Hi there. Recently i encountered this error when i migrated visual studio 2008 windows application to vs 2012 . Here i am dragging report viewer to control on windows form, then i encountered a long list of error message
Problem is project reference is enabled for version 10.0.0 for report viewer but toolbox is adding 126.96.36.199 version.
Solution: just add the System.ReportViewer.Winforms 188.8.131.52 version remove 10.0.0.0 version.
You will get these kind of designer errors when you migrate to higher version. Just check the references added to project properly.
Hope it helps you.