I met a problem when I am learning the ASP.NET. I defined the Application_Error event handler in the global.asax, and then tried to throw an exception from a webpage, defined this webpage as the start page of this project. When I run the project, the system always returns a system defined error page, and doesnt run any code I defined in the Application_Error event handler. Can anybody tell me why? (When I run the project, it run in debug mode in Visual Studio enviroment) Thanks.