# .NET and More > Silverlight >  [RESOLVED] version 3 to 4

## arkiboys

I am in th eprocess of changing a silverlight 3 application to silverlight 4.
Is it necessary to check the references in the silverlight app. so that if any refers to version 3 then change to version 4 references?

Thanks

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## gep13

Hello,

Are you using Visual Studio 2010 to do this?

If so, since it can target both SL 3 adn SL4, it should take care of the process for you.

Gary

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## MattP

Duplicate thread here: http://www.vbforums.com/showthread.php?t=634999

Issue was a lack of Silverlight Developer Tools for version 4.

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