Custom Error Page in ASP.Net

Whenever any error occurs during the execution of our ASP.net applications we normally show an error page. It is done to hide the technical error information to the user and show a generic error message. This article will help us to implement the custom error page for ASP.Net application. I will list some of the possible ways that we can use to show the error page to the user. We redirect the user to a custom error page by 3 ways.
Using Page_Error Event
Using Application_Error event in Global.asax
Using Web.Config

Using Page_Error Event:
Using this event we can seize the error at page level. Instead of writing this event at every page we can move to BasePage class like below.

public class BasePage : System.Web.UI.Page
{
void Page_Error(object sender, EventArgs e)
{
Server.Transfer(“Error.aspx”);
}
}
And then we can inherit every page with this object instead of Page object. So an aspx.cs file will look like,
public partial class _Default : BasePage
{
protected void Page_Load(object sender, EventArgs e)
{
}
}

With this approach we can prevent the redundant code in every page. If we want to handle error differently in different pages then we can write this event in everypage.
In error page we can get the actual exception or error information using Server.GetLastError() method like below,

public partial class Error : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Response.Write(Server.GetLastError());
}
}

Most of the time it is not advisable to show the error information using Server.GetLastError() because the error message will be technical which is not appropriate to the enduser.

Using Application_Error event in Global.asax
We can trap the error in Application_Error if it is not trapped in Page_Error event. We can log the error information into a Eventlog,etc..
void Application_Error(object sender, EventArgs e)
{
//Event log code
Server.ClearError();
}
Using Web.Config
This is most commonly used approach using configuration settings.

Note:
If we trapped the error in Application_Error event and cleared the error using Server.ClearError(), then section won’t work because the error is cleared. So we can log the error into eventlog in Application_Error event and then redirect to a generic error page using section. Now the enduser will see the generic error page and we can enough technical information in event log for fixing the error.