workflow rehosted designer 4.0 error after installing .Net 4.5

After installing .Net 4.5, my rehosted workflow designer is suddenly giving me errors at runtime :

the project is still targeted at 4.0 (and it should remain that way)
it compiles without errors
when I try to load an existing XAML, an exception occurs.

_workflowDesigner.Text = xaml;

_workflowDesigner.Load();

exception on Load method: can not convert an object of type System.Windows.Input.CommandBinding to System.Activities.Presentation.View.DesignerView

Solution

That looks like maybe a versioning issue? Or resource localization bug. Since you mention Visual Studio 2012 it sounds like maybe it comes from having a combination of .Net 4.5 and .Net Client Profile 4.0 DEU.

Note that installing VS 2012 will always install .Net 4.5.

It seems like there is a .Net 4.5 DEU Language pack. I am guessing that may have better compatibility with .Net 4.5. Could you try uninstalling the Framework 4 one, and installing this one instead? http://www.microsoft.com/de-de/download/details.aspx?id=30667

Reference : http://social.msdn.microsoft.com/Forums/da-DK/wfprerelease/thread/19bdb5c5-ee04-48b8-bd8b-5a45d0fc2de6