Customizing the exception page in asp.net

Asp.net| pages are sorted by exception-handling precedence
(0) Add code to the Global.asax Application_Error
protected void Application_Error (Object sender, EventArgs e)
{
Context.clearerror ();
Response.Write ("Error");
Response.Redirect ("errorpage.htm");
}
(1) webform1_error in the background code
Add exception handling code in Ui.page Error event in properties of ASPX page
private void Webform1_error (object sender, System.EventArgs e)
{
Exception Ex=server.getlasterror ();
session["Error"]=ex. message;
Server.ClearError ();
Response.Redirect ("error.aspx");
}
(2) Add ErrorPage to HTML code
Errorpage= "Http://www.21cn.com"
(3) Add exception handling page in Web.config
<customerrors mode= "on" defaultredirect= "error.aspx" >
<error statuscode= "401" redirect= "error.aspx"/>
<error statuscode= "404" redirect= "http://www.sina.com.cn"/>
</customErrors>
(4) Setting the Exception handling page in IIS