In this article I will explain with an example, how to create a simple Error Log Text File in ASP.Net using C# and VB.Net.
Writing or Logging errors (exceptions) occurring in ASP.Net application to Text files makes it easier to find the cause of the error as the Error Log Text File can be easily opened using the basic Notepad application in Windows.
 
 
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.
<asp:Button Text="Click to Raise Exception" runat="server" OnClick="RaiseException"/>
 
 
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/yyyy hh: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/yyyy hh: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
Create simple Error Log Text File in ASP.Net using C# and VB.Net
 
 
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