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

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

OK, I found this post: http://msdn.microsoft.com/en-us/library/aa479319.aspx

with this very illustrative diagram:

diagram http://i.msdn.microsoft.com/Aa479319.customerrors_01(en-us,MSDN.10).gif

in essence, to get at those exception details i need to store them myself in Global.asax, for later retrieval on my custom error page.

it seems the best way is to do the bulk of the work in Global.asax, with the custom error pages handling helpful content rather than logic.

Answer 2

Try using something like Server.Transfer("~/ErrorPage.aspx"); from within the Application_Error() method of global.asax.cs

Then from within Page_Load() of ErrorPage.aspx.cs you should be okay to do something like: Exception exception = Server.GetLastError().GetBaseException();

Server.Transfer() seems to keep the exception hanging around.

Answer 3

Whilst there are several good answers here, I must point out that it is not good practice to display system exception messages on error pages (which is what I am assuming you want to do). You may inadvertently reveal things you do not wish to do so to malicious users. For example Sql Server exception messages are very verbose and can give the user name, password and schema information of the database when an error occurs. That information should not be displayed to an end user.

Answer 4

Here is my solution..

In Global.aspx:

void Application_Error(object sender, EventArgs e)
    {
        // Code that runs when an unhandled error occurs

        //direct user to error page 
        Server.Transfer("~/ErrorPages/Oops.aspx"); 
    }

In Oops.aspx:

protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
            LoadError(Server.GetLastError()); 
    }

    protected void LoadError(Exception objError)
    {
        if (objError != null)
        {
            StringBuilder lasterror = new StringBuilder();

            if (objError.Message != null)
            {
                lasterror.AppendLine("Message:");
                lasterror.AppendLine(objError.Message);
                lasterror.AppendLine();
            }

            if (objError.InnerException != null)
            {
                lasterror.AppendLine("InnerException:");
                lasterror.AppendLine(objError.InnerException.ToString());
                lasterror.AppendLine();
            }

            if (objError.Source != null)
            {
                lasterror.AppendLine("Source:");
                lasterror.AppendLine(objError.Source);
                lasterror.AppendLine();
            }

            if (objError.StackTrace != null)
            {
                lasterror.AppendLine("StackTrace:");
                lasterror.AppendLine(objError.StackTrace);
                lasterror.AppendLine();
            }

            ViewState.Add("LastError", lasterror.ToString());
        }
    }

   protected void btnReportError_Click(object sender, EventArgs e)
    {
        SendEmail();
    }

    public void SendEmail()
    {
        try
        {
            MailMessage msg = new MailMessage("webteam", "webteam");
            StringBuilder body = new StringBuilder();

            body.AppendLine("An unexcepted error has occurred.");
            body.AppendLine();

            body.AppendLine(ViewState["LastError"].ToString());

            msg.Subject = "Error";
            msg.Body = body.ToString();
            msg.IsBodyHtml = false;

            SmtpClient smtp = new SmtpClient("exchangeserver");
            smtp.Send(msg);
        }

        catch (Exception ex)
        {
            lblException.Text = ex.Message;
        }
    }