an unhandled exception occurred in the silverlight application sharepoint 2010

In SharePoint 2010 you may recieve the error "an unhandled exception occurred in the silverlight application sharepoint 2010" on sites which have been upgraded. This will generally occur when trying to create new Lists, Libraries, Sites or Pages. This happens because silverlight is unable to connect to the Windows Communication Foundation endpoint for enabling the Client Object Model, if Security validation is Off. To resolve the problem navigate to Central Administration and enable the Web Page Security Validation for the Web Application. Do the following:

1. Open Central Administration
2. Select Application Management
3. Select Manage Web Applications
4. Select the Web Application where the error occurs
5. In the ribbon, select General Settings
6. In the Web Application General Settings dialog box, find Web Page Security Validation and select On