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

It worked for me. in MVC 5

in ~\Global.asax

void Application_Error(object sender, EventArgs e)
{
    FTools.LogException();
    Response.Redirect("/Error");
}

---

in ~\Controllers Create ErrorController.cs

using System.Web.Mvc;

namespace MVC_WebApp.Controllers
{
    public class ErrorController : Controller
    {
        // GET: Error
        public ActionResult Index()
        {
            return View("Error");
        }
    }
}

---

in ~\Models Create FunctionTools.cs

using System;
using System.Web;

namespace MVC_WebApp.Models
{
    public static class FTools
    {
        private static string _error;
        private static bool _isError;

        public static string GetLastError
        {
            get
            {
                string cashe = _error;
                HttpContext.Current.Server.ClearError();
                _error = null;
                _isError = false;
                return cashe;
            }
        }
        public static bool ThereIsError => _isError;

        public static void LogException()
        {
            Exception exc = HttpContext.Current.Server.GetLastError();
            if (exc == null) return;
            string errLog = "";
            errLog += "**********" + DateTime.Now + "**********\n";
            if (exc.InnerException != null)
            {
                errLog += "Inner Exception Type: ";
                errLog += exc.InnerException.GetType() + "\n";
                errLog += "Inner Exception: ";
                errLog += exc.InnerException.Message + "\n";
                errLog += "Inner Source: ";
                errLog += exc.InnerException.Source + "\n";
                if (exc.InnerException.StackTrace != null)
                {
                    errLog += "\nInner Stack Trace: " + "\n";
                    errLog += exc.InnerException.StackTrace + "\n";
                }
            }
            errLog += "Exception Type: ";
            errLog += exc.GetType().ToString() + "\n";
            errLog += "Exception: " + exc.Message + "\n";
            errLog += "\nStack Trace: " + "\n";
            if (exc.StackTrace != null)
            {
                errLog += exc.StackTrace + "\n";
            }
            _error = errLog;
            _isError = true;
        }
    }
}

---

in ~\Views Create Folder Error and in ~\Views\Error Create Error.cshtml

@using MVC_WebApp.Models
@{
    ViewBag.Title = "Error";
    if (FTools.ThereIsError == false)
    {
        if (Server.GetLastError() != null)
        {
            FTools.LogException();
        }
    }
    if (FTools.ThereIsError == false)
    {
        <br />
        <h1>No Problem!</h1>
    }
    else
    {
        string log = FTools.GetLastError;
        <div>@Html.Raw(log.Replace("\n", "<br />"))</div>
    }
}

---

If you enter this address localhost/Error

---

And if an error occurs

As can be instead of displaying errors, variable 'log' to be stored in the database

Source: Microsoft ASP.Net

Answer 2

This related to these 2 topics below, I want get both GetHtmlErrorMessage and Session on Error page.

Session is null after ResponseRewrite

Why is HttpContext.Session null when redirectMode = ResponseRewrite

I tried and see solution which no need Server.Transfer() or Response.Redirect()

First: remove ResponseRewrite in web.config

Web.config

<customErrors defaultRedirect="errorHandler.aspx" mode="On" />

Then Global.asax

    void Application_Error(object sender, EventArgs e)
    {
         if(Context.IsCustomErrorEnabled)
         {     
            Exception ex = Server.GetLastError();
            Application["TheException"] = ex; //store the error for later
         }
    }

Then errorHandler.aspx.cs

        protected void Page_Load(object sender, EventArgs e)
            {       
                string htmlErrorMessage = string.Empty ;
                Exception ex = (Exception)Application["TheException"];
                string yourSessionValue = HttpContext.Current.Session["YourSessionId"].ToString();

                //continue with ex to get htmlErrorMessage 
                if(ex.GetHtmlErrorMessage() != null){              
                    htmlErrorMessage = ex.GetHtmlErrorMessage();
                }   
                // continue your code
            }

For references

http://www.developer.com/net/asp/article.php/3299641/ServerTransfer-Vs-ResponseRedirect.htm

Answer 3

I think you have a couple of options here.

you could store the last Exception in the Session and retrieve it from your custom error page; or you could just redirect to your custom error page within the Application_error event. If you choose the latter, you want to make sure you use the Server.Transfer method.

Answer 4

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.

Answer 5

One important consideration that I think everybody is missing here is a load-balancing (web farm) scenario. Since the server that's executing global.asax may be different than the server that's about the execute the custom error page, stashing the exception object in Application is not reliable.

I'm still looking for a reliable solution to this problem in a web farm configuration, and/or a good explanation from MS as to why you just can't pick up the exception with Server.GetLastError on the custom error page like you can in global.asax Application_Error.

P.S. It's unsafe to store data in the Application collection without first locking it and then unlocking it.

Answer 6

A combination of what NailItDown and Victor said. The preferred/easiest way is to use your Global.Asax to store the error and then redirect to your custom error page.

Global.asax:

    void Application_Error(object sender, EventArgs e) 
{
    // Code that runs when an unhandled error occurs
    Exception ex = Server.GetLastError();
    Application["TheException"] = ex; //store the error for later
    Server.ClearError(); //clear the error so we can continue onwards
    Response.Redirect("~/myErrorPage.aspx"); //direct user to error page
}

In addition, you need to set up your web.config:

  <system.web>
    <customErrors mode="RemoteOnly" defaultRedirect="~/myErrorPage.aspx">
    </customErrors>
  </system.web>

And finally, do whatever you need to with the exception you've stored in your error page:

protected void Page_Load(object sender, EventArgs e)
{

    // ... do stuff ...
    //we caught an exception in our Global.asax, do stuff with it.
    Exception caughtException = (Exception)Application["TheException"];
    //... do stuff ...
}