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I found, if I turn on Unobtrusive validation in mvc 3, after press insert/update button, ModelState errors not display in edit popup form.
<add key="UnobtrusiveJavaScriptEnabled" value="true"/> [GridAction][HttpPost]public ActionResult insertRole(long? id){ ModelState.AddModelError("code", "some error"); return View(new GridModel(base.loadRoles().roles));}