Here's the simple code that I wrote not long ago to catch exception on page level and write them down in applications log file into applications root directory:
Protected Sub Page_Error(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Error
Dim err As Exception = Server.GetLastError()
Dim write As String
write = err.Message
Dim fileExists As Boolean
fileExists = My.Computer.FileSystem.FileExists("C:\Inetpub\wwwroot\test\error.log")
If fileExists = False Then
My.Computer.FileSystem.WriteAllText("C:\Inetpub\wwwroot\test\error.log", String.Empty, False)
My.Computer.FileSystem.WriteAllText("C:\Inetpub\wwwroot\test\error.log", _
"/***************** " & DateTime.Now() & " *****************/" & vbCrLf & vbCrLf & _
"Type: Page Level Error" & vbCrLf & _
"Client IP: " & Request.ServerVariables("Remote_Addr") & vbCrLf & _
"Page: " & Request.UrlReferrer.AbsoluteUri & vbCrLf & _
"Error: " & write & vbCrLf & vbCrLf & _
"----------------------------------------------------------" & vbCrLf & vbCrLf, True)
Else
My.Computer.FileSystem.WriteAllText("C:\Inetpub\wwwroot\test\error.log", _
"/***************** " & DateTime.Now() & " *****************/" & vbCrLf & vbCrLf & _
"Type: Page Level Error" & vbCrLf & _
"Client IP: " & Request.ServerVariables("Remote_Addr") & vbCrLf & _
"Page: " & Request.UrlReferrer.AbsoluteUri & vbCrLf & _
"Error: " & write & vbCrLf & vbCrLf & _
"----------------------------------------------------------" & vbCrLf & vbCrLf, True)
End If
Server.ClearError()
Response.Redirect(Request.UrlReferrer.AbsoluteUri)
End Sub