I am getting folloeing error while trying to expand a particular node in episerver CMS 5 The target 'FullRegion$explorerTreeView$treeView' for the callback could not be found or did not implement ICallbackEventHandler" after moving the web application from .NET3.5 to .NET4.0.
If any one came across the following problem please help.
thanks in advance.
EPiServer CMS 5 does not officially support .NET 4.0.
For your specific problem, you can try checking if the line <xhtmlConformance mode="Legacy" /> exists in your web.config file, and if it does - remove it.