When Upgrading the project from Silverlight 2 to Silverlight 3, we hav to make some changes in the aspx file.
Reason : – asp:Silvelright and object tags is not modified.
Change the ”minRuntimeVersion” attribute of object tag & “MinimumVersion” attribute of asp:Silverlight to “3.0.40307.0″
<param name=”minRuntimeVersion” value=”3.0.40307.0″ />
<asp:Silverlight MinimumVersion=”3.0.40307.0″ />
In addition, if you use an object tag, make sure to update the link to install the newest runtime to: http://go.microsoft.com/fwlink/?LinkID=141205
courtsey :- A Dullard’s Guide
