In this article I will explain with an example, how to implement error logging and exception handling in ASP.Net using C# and VB.Net.
 
 
 

HTML Markup

The following HTML Markup consists of an ASP.Net Button control which will raise an Exception and the exception (error) Message details will be displayed.
<form id="form1" runat="server">
    <asp:Button Text="Click to Raise Exception" runat="server" OnClick="RaiseException" />
</form>
 
 

Namespaces

You will need to import the following namespace.
C#
using System.IO;
 
VB.Net
Imports System.IO
 
 

Creating simple Error Log Text File in ASP.Net

The following event handler is raised when the Button is clicked. An exception is raised by converting a string value to integer inside a Try-Catch block.
The raised Exception is caught in the Catch block and the LogError function is called.
Inside the LogError function, the details of the exception (error) are written to an Error Log Text file along with current date and time.
C#
protected void RaiseException(object sender, EventArgs e)
{
    try
    {
        int i = int.Parse("Mudassar");
    }
    catch (Exception ex)
    {
        this.LogError(ex);
    }
}
 
private void LogError(Exception ex)
{
     string message = string.Format("Time: {0}", DateTime.Now.ToString("dd/MM/yyyyhh:mm:ss tt"));
     message += Environment.NewLine;
     message += "-----------------------------------------------------------";
     message += Environment.NewLine;
     message += string.Format("Message: {0}", ex.Message);
     message += Environment.NewLine;
     message += string.Format("StackTrace: {0}", ex.StackTrace);
     message += Environment.NewLine;
     message += string.Format("Source: {0}", ex.Source);
     message += Environment.NewLine;
     message += string.Format("TargetSite: {0}", ex.TargetSite.ToString());
     message += Environment.NewLine;
     message += "-----------------------------------------------------------";
     message += Environment.NewLine;
     string path = Server.MapPath("~/ErrorLog/ErrorLog.txt");
     using (StreamWriter writer = new StreamWriter(path, true))
     {
        writer.WriteLine(message);
        writer.Close();
     }
}
 
VB.Net
Protected Sub RaiseException(sender As Object, e As EventArgs)
    Try
        Dim i As Integer = Integer.Parse("Mudassar")
    Catch ex As Exception
        Me.LogError(ex)
    End Try
End Sub
 
Private Sub LogError(ex As Exception)
     Dim message As String = String.Format("Time: {0}", DateTime.Now.ToString("dd/MM/yyyyhh:mm:ss tt"))
     message += Environment.NewLine
     message += "-----------------------------------------------------------"
     message += Environment.NewLine
     message += String.Format("Message: {0}", ex.Message)
     message += Environment.NewLine
     message += String.Format("StackTrace: {0}", ex.StackTrace)
     message += Environment.NewLine
     message += String.Format("Source: {0}", ex.Source)
     message += Environment.NewLine
     message += String.Format("TargetSite: {0}", ex.TargetSite.ToString())
     message += Environment.NewLine
     message += "-----------------------------------------------------------"
     message += Environment.NewLine
     Dim path As String = Server.MapPath("~/ErrorLog/ErrorLog.txt")
     Using writer As New StreamWriter(path, True)
        writer.WriteLine(message)
        writer.Close()
     End Using
End Sub
 
 

Screenshot

Error logging and Exception handling in ASP.Net using C# and VB.Net
 
 

Downloads

Download Code