ASP.NET custom error page - Server.GetLastError() is null

Question

I have a custom error page set up for my application:

<customErrors mode="On" defaultRedirect="~/errors/GeneralError.aspx"
/>

In Global.asax, Application_Error(), the following code works to get the exception details:

  Exception ex = Server.GetLastError();
  if (ex != null)
    {
        if (ex.GetBaseException() != null)
            ex = ex.GetBaseException();
    }

By the time I get to my error page (~/errors/GeneralError.aspx.cs), Server.GetLastError() is null

Is there any way I can get the exception details on the Error Page, rather than in Global.asax.cs ?

ASP.NET 3.5 on Vista/IIS7

Answer 1

Looking more closely at my web.config set up, one of the comments in this post is very helpful

in asp.net 3.5 sp1 there is a new parameter redirectMode

So we can amend customErrors to add this parameter:

<customErrors mode="RemoteOnly" defaultRedirect="~/errors/GeneralError.aspx" redirectMode="ResponseRewrite" />

the ResponseRewrite mode allows us to load the «Error Page» without redirecting the browser, so the URL stays the same, and importantly for me, exception information is not lost.