Hah - so after posting this I thought I'd just play around a bit more and see if I could fix it.

Seems that calling databind on the grid's Init event fixes our problem.

        protected void WebHierarchicalDataGrid1_Init(object sender, EventArgs e)
        {
            WebHierarchicalDataGrid1.DataBind();
        }

We were simply binding to SQLDataSources in the markup and seems this is not enough, need to forcibly databind in the codebehind.  It's like the grid is doing some events internally in the wrong order or something and forcing the databind fixes it up.

Anyway, this fixes it for us and hopefully for anyone else out there who comes across this problem.

Over and out.

Does anyone know if this actually got fixed?

We are using 13.1.20131.2107 and have this exact same problem on a WebHierarchicalDataGrid.  Removing the <%...%> from the template field doesn't help.

If we have TemplateDataField on its own the grid works fine, if we have DropDownProvider on its own grid works fine.

If we have BOTH, we get this error....

Exception message: Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

Hi Rado,

Does the Service Release on July 29 include this item?

Also, is there any release note of service release for reference?

So do template fields not work at all in the webdatagrid? I'm using 10.2 and as soon as I add a template to a template field I get an error on postback.

<ig:TemplateDataField Key="Img" Header-Text="Img">
           <ItemTemplate>
                    <asp:Label ID="Label1" runat="server">blah</asp:Label>
           </ItemTemplate>
          <Header Text="Img" />
  </ig:TemplateDataField>

Removing the item template causes the error to go away.