We are not aware of the mentioned issue with RadGrid's Skins in SharePonint 2013.
What I can suggest is that you try the following troubleshooting steps:
- If you are not using the latest official version of Telerik UI - 2014.2.618, does upgrading to it fixes the issue?
- In order for Telerik UI controls to work properly the version of all of the .DLL files (i.e., Telerik.Web.UI.dll, Telerik.Web.UI.Skins.dll and Telerik.Web.Design.dll) must match. Can you ensure that?
The obsolete built-in skins Transparent, Hay, Forest and Sitefinity have been removed from the Telerik.Web.UI.Skins assembly as of the Q1 2014 release of Telerik UI for ASP.NET AJAX. More information on the matter is available in the release notes (see the All Controls section) Q1 2014 and this sticky note (scroll to the bottom of the page).
Can you ensure that you are not using these skins?
If the above steps, however, do not help it would be better to provide us with the problematic Visual Web Part, so that we can make an investigation locally. Could you also tell us what is the error message that is thrown?
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