Update. Turned out that I had inadvertantly re-named a label control (while making changes to the form). The label control is referenced in the function called by the commandbutton. Took me awhile to figure it out since the error message wasn't really all that helpful... and also because I haven't figured out how to get the debugger to work and therefore can't step through the code.

>Hi,
>
>In the process of making major changes to a web form, I renamed the original 'DataDictDownload' to 'DataDictDownload_old'.
>
>I then backed-up 'DataDictDownload_old' to another folder and deleted it from the app folder - now when I run 'DataDictDownload', whenever I try to postback to the server (i.e. when clicking a command button), I get the following error:
>
>

>
>[NullReferenceException: Object reference not set to an instance of an object.]
>   LuckyDogSystems.DataDictDownload.fnValidateInput()
>   LuckyDogSystems.DataDictDownload.cmdDownload_Click(Object sender, EventArgs e)
>   System.Web.UI.WebControls.Button.OnClick(EventArgs e)
>   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
>   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
>   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
>   System.Web.UI.Page.ProcessRequestMain()
>
>

>
>In fact, I even added a new commandbutton with one line of code - simply setting the visible property of a label to false. I received the same error on clicking this new button ...
>
>I can't figure it out, because I do have the '.aspx', '.aspx.resx' and '.aspx.vb' files in place. Any ideas where the problem may be?