Using Kendo UI in MVC4 I have a Grid that makes Ajax calls for data back into the Controller:
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Try to raise the exception and check whether it is prompting an alert message or not.
For Kendo grid, there is error event which might be helpful for you.
http://docs.kendoui.com/documentation/getting-started/using-kendo-with/aspnet-mvc/migration/widgets/grid
We used telerik mvc grids which automatically displays alert messages if there is any error while binding.
http://www.telerik.com/community/forums/aspnet-mvc/grid/exception-handling.aspx
http://www.telerik.com/community/forums/aspnet-mvc/grid/how-to-do-error-handling-in-gridaction-methods.aspx