You should follow these steps when upgrading the version of RadControls for ASP.NET AJAX in your project:
1. Run the installer of Telerik AJAX controls for SharePoint for the version you want to upgrade to (which you have already done).
2. Use the version number of the new release in every reference to the assemblies that includes a fully qualified name in web.config and in the user controls. For example:
Telerik.Web.UI, Version=2010.3.1109.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4"
should be replaced with
Telerik.Web.UI, Version=2012.3.1308.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4"
3. If there are references to an old version of Telerik.Web.UI, for example 2010.3.1109.35
, you need the following dependent assembly element in order for all the references to be redirected to the new version of the assembly:
the Telerik team
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