Hi,

I have a web site with an UpdatePanel, a Label within that panel and a
Button outside the panel. All controls are created programatically (see
code below).
When I click the button to update the label's text, I get a
NullReferenceException in the page's Render method. My own code runs
without any problems.

Any one with some ideas? I already did some Google reseach but came out
with nothing that would help be :(

<code>
public partial class test : System.Web.UI.Page {

  UpdatePanel up;
  Label l1;
  Panel p;
  UpdateProgress upp;
  Button b;
  UpdateProgressOverlayExtender upoe;

  protected override void OnPreInit(EventArgs e) {
    base.OnPreInit(e);
    // create dynamic controls
    up = new UpdatePanel();

    p = new Panel();
    up.ContentTemplateContainer.Controls.Add(p);

    l1 = new Label();
    p.Controls.Add(l1);

    this.form1.Controls.Add(up);
     
    b = new Button();
    this.form1.Controls.Add(b);
  }

  protected override void OnLoad(EventArgs e) {
    base.OnLoad(e);

    // control properties
    l1.ID = "l1";

    // some backgroud
    p.Style.Value =
      "width:100%; height:100px; text-align:center; " +
      "background:#3366a4; border:solid 1px black;";

    up.ID = "up";
    up.ChildrenAsTriggers = false;
    up.UpdateMode = UpdatePanelUpdateMode.Conditional;

    b.Text = "Update Panel";
    b.ID = "b";
    b.Click += new EventHandler(this.ButtonClick);

    // add button as update trigger
    AsyncPostBackTrigger apt = new AsyncPostBackTrigger();
    apt.ControlID = b.ClientID;
    up.Triggers.Add(apt);

    this.ScriptManager1.RegisterAsyncPostBackControl(b);
  }

  protected void ButtonClick(object sender, EventArgs e) {
    // wait a litte
    Thread.Sleep(2000);
    // set label text
    l1.Text = "Panel refreshed at " + DateTime.Now.ToString();
  }

  protected override void Render(HtmlTextWriter writer) {
    try {
      // here the error occurs
      base.Render(writer);
    } catch (Exception ex) {
      writer.Write(ex.ToString());
    }
  }
}
</code>

Thanks,
Tobi