Moving from Silverlight 3 to Silverlight 4

Question

I moved my app from silverlight 3 VS2010 to a system having Silverlight 4 and VS 2010. When I open the Solution I get the following error in the MainPAge.xml. What is wrong.

Could not resolve mscorlib for target framework 'Silverlight,Version=v3.0'. This can happen if the target framework is not installed or if the framework moniker is incorrectly formatted.

Answer 1

Open the 'Properties' of your projects an verify that the "Target Silverlight Version" in the Section "Silverlight" is set to Silverlight 4.

Since you developed your application for Silverlight 3, the "Target Silverlight Version" is set to 3 and the "system" has only Version 4 installed. So Visual Studio cannot resolve the Silverlight assemblies for Version 3.