Question

VS 2008 / ASP.Net

I have a deployed a ASP.Net Web Application on Windows 2003 Server. For some reasons, it throws an error.

Application works great on my local computer. Either from source code or hosted on my local machine (Windows XP).

How to trace error on a deployed ASP.Net Web Application ?

Error :

Object reference not set to an instance of an object. Description: An
unhandled exception occurred during the execution of the current web
request. Please review the stack trace for more information about the
error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not
set to an instance of an object.

Source Error:

An unhandled exception was generated during the execution of the
current web request. Information regarding the origin and location of
the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   _Default.ExportRx30ToSalisburyAccessDB() +351
   _Default.Button1_Click(Object sender, EventArgs e) +5
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

Source code : Which i am facing this error ..

try
{

        Access.Application access1 = new Access.Application();

        // Open the Access database for exclusive access
        string sSalisburyAccessDB = Server.MapPath("~/App_Data/Salisbury.mdb");

        access1.OpenCurrentDatabase(sSalisburyAccessDB, true, null);

        // Drop the existing table data

        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "drug");
        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "patplan");
        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "plans");
        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "price");
        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "rx");
        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "patient");
        access1.DoCmd.DeleteObject(Access.AcObjectType.acTable, "plntrak");

        // Run the saved import
        access1.DoCmd.RunSavedImportExport("SalisburyODBC");

        // Close the database
        access1.CloseCurrentDatabase();

        // Quit MS Access
        access1.Quit(Access.AcQuitOption.acQuitSaveAll);

        Response.Write("successful");

    }
    catch (Exception ex)
    {
        Response.Write(ex.InnerException.Message);
    }

Answer 1

Try running your app in IIS Express instead of Cassini (the built-in Visual Studio development web server). They behave differently and you might have a better shot at recreating the issue in your development environment. IIS Express runs just like real IIS so there are fewer surprises when you deploy your application.