Exception Handling in IIS7 Integrated Pipeline Mode - iis-7

Question

I have an application hosted on IIS7 running in Integrated mode. I'm handling errors by putting the following into Web.config:
<httpErrors errorMode="DetailedLocalOnly" existingResponse="Replace"
defaultResponseMode="ExecuteURL" defaultPath="/Error.aspx">
<remove statusCode="500" />
<error statusCode="500" path="/Error.aspx" responseMode="ExecuteURL" />
</httpErrors>
(Because this is Integrated mode the <customErrors> block is not used.)
I want to automatically send emails every time an exception is generated. But the problem is that within Error.aspx I can't figure out how to get a reference to the exception. I tried this:
Dim oEx As Exception = Server.GetLastError()
But it returns Nothing. I also tried HttpContext.Current.Error() and HttpContext.Current.AllErrors and those don't work either.
In a custom error page running under IIS7 Integrated mode, how do I get a reference to the handled exception?

Answer 1

You need to intercept the error, either in Global.asax or a custom IHttpModule implementation as follows:
public class UnhandledExceptionHandlerModule : IHttpModule {
private HttpApplication application;
public void Init(HttpApplication application)
{
this.application = httpApplication;
this.application.Error += Application_Error;
}
public void Dispose()
{
application = null;
}
protected internal void Application_Error(object sender, EventArgs e)
{
application.Transfer("~/Error.aspx");
}
}
Then, in Error.aspx.cs:
protected void Page_Load(object sender, EventArgs e) {
Response.StatusCode = 500;
// Prevent IIS from discarding our response if
// <system.webServer>/<httpErrors> is configured.
Response.TrySkipIisCustomErrors = true;
// Send error in email
SendEmail(Server.GetLastError());
// Prevent ASP.NET from redirecting if
// <system.web>/<customErrors> is configured.
Server.ClearError();
}