Not able to read exception details on Custom Error Page

Question

User646364117 posted

I  am transferring to a custom error page.

When I GetLastError it is Nothing so getting null exception error

I have a different version where I use Session variables for the ex message and stack trace and I can consume these on the error page.

Why doesn't this method work?

This is code behind of error page

Imports System.Configuration
Imports System.Text
Imports System.Diagnostics

Partial Class Errors
    Inherits System.Web.UI.Page


    Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        If Not Page.IsPostBack Then
            Dim ex As Exception
            ex = Server.GetLastError '<< Get null reference error here

            Server.ClearError()
        End If


    End Sub
End Class

This is code behind of page where error is thrown

    Protected Sub BindGvCategoryTemplate()
        Try
            Throw New DuplicateTemplateException("Exception Occured in GetCategoryTemplateDataTable - Line 115")

            Dim dtCategoryTemplate As DataTable
            dtCategoryTemplate = GetCategoryTemplateDataTable()
            gvCategoryTemplate.DataSource = dtCategoryTemplate
            gvCategoryTemplate.DataBind()

            Exit Sub
        Catch ex As Exception


            If ex IsNot Nothing Then


                Server.Transfer("~/Errors.aspx")
            End If
        End Try
    End Sub

Answer 1

User475983607 posted

I recommend reading the official ASP.NET error handling docs and following the pattern.

https://docs.microsoft.com/en-us/aspnet/web-forms/overview/getting-started/getting-started-with-aspnet-45-web-forms/aspnet-error-handling

Server.Transfer("~/Errors.aspx", true)

Server.transfer docs.

https://docs.microsoft.com/en-us/dotnet/api/system.web.httpserverutility.transfer?view=netframework-4.8

Answer 2

User1535942433 posted

Hi sg48asp,

Accroding to your description and codes,as far as I think,GetLastError() need to be writted in Global.asax file.Besides,you also could amend customErrors in web.config to read exception details.

More details,you could refer to below codes:

<customErrors mode="RemoteOnly" defaultRedirect="~/errors/GeneralError.aspx" redirectMode="ResponseRewrite" />

More details,you could refer to below article:

https://forums.asp.net/t/2121806.aspx?Server+GetLastError+Returns+Null

Best regards,

Yijing Sun