The Core Grid throws an exception when setting its toolbar template through the ClientTemplateId option. The issue is a regression introduced in version 2025.2.520.
.ToolBar(toolbar => {
toolbar.ClientTemplateId("myTemplate");
})
An exception is thrown:
NullReferenceException: Object reference not set to an instance of an object
The configuration works without throwing exceptions.
Use the alternative way of setting the toolbar template, on the Grid's root level:
@(Html.Kendo().Grid <MyModel>()
.Name("grid")
.ToolBarClientTemplateId("myTemplate")