Error

System.InvalidCastException: Unable to cast object of type 'ASP._webcontent_masterpages_nf_c_master' to type '_WebContent_MasterPages_2013_C'.
   at _WebContent_PageContent_MyAccount_Register.Page_PreRenderComplete(Object sender, EventArgs e)
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Exception of type 'System.Web.HttpUnhandledException' was thrown.

System.Web