UserControls in ASP.NET (4.0) inherit from System.Web.UI.UserControl. VisualStudio intellisense suggest OnError as valid override of TemplateControl. At runtime .NET ignores this error handling. Only the OnError at Page-Level gets invoked. Did i miss anything or is there a design issue? public partial class Sample : System.Web.UI.UserControl { protected override void OnError(EventArgs e) { // Never reach ;o) base.OnError(e); } }