ASP.NET:How to write error messages into a text file using a simple httpModule

In one of my previous posts, I mentioned about how to troubleshoot some issues with the use of a module. In this post, I will show you how a similar module could be of use when you want to log all the errors in a text file for troubleshooting purposes. Please ensure that C:\Temp folder has Write access for the account that is running the IIS Worker Process. Here is the code for the module...

 using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.IO;
namespace myModules
{
    class Trigger:IHttpModule
    {
        public void Init(System.Web.HttpApplication context)
        {
            context.EndRequest += new EventHandler(this.EndRoutine);
        }
        public void EndRoutine(object o, EventArgs e)
        {
            HttpApplication myApp;
            myApp = (HttpApplication)o;
            HttpContext c = myApp.Context;
            if (myApp.Context.AllErrors != null)
            {
                StreamWriter sw = new StreamWriter("C:\\Temp\\ErrorList.txt", true);
                foreach (Exception ex in myApp.Context.AllErrors)
                {
                    sw.WriteLine("Error occurred at #{0}", DateTime.Now.ToString());
                    sw.WriteLine("Error occurred in page #{0}", c.Request.FilePath);
                    sw.WriteLine(ex.InnerException.Message);
                    sw.WriteLine(ex.InnerException.StackTrace);
                    sw.WriteLine();
                }
                sw.Dispose();
            }
        }
        public void Dispose()
        {
            //Nothing to Dispose as of now
        }
    }
}

You can save the downloaded file to the bin folder of your web application and add the following to the web.config...

         <httpModules>
            <add name="Trigger" type="myModules.Trigger, myModules"/>
        </httpModules>

Here is the sample output (C:\Temp\ErrorList.txt) for one of the applications where I have used the Throw New AppDomainUnloadedException or similar lines to create the error...

Hope this helps,
Rahul

Quote of the day:
The nice thing about standards is that there are so many of them to choose from. - Andrew S. Tanenbaum

Posted at > 6:10 PM IST

myModules.zip