ASP.NET UpdatePanel Error htmlfile: Unknown runtime error, updatePanelElement.innerHTML=rendering

Question

I get this error when debugging my ASP.NET web application after I trigger an UpdatePanel:

htmlfile: Unknown runtime error

and "updatePanelElement.innerHTML=rendering" is highlighted in a ScriptResource.axd file.

Solution 1

This seems to happen because I've got my UpdatePanel within an ordered list <ol> container. And I've got list item <li> tags within my UpdatePanel's ContentTemplate.

<ol>
    <li>...</li>
    <asp:UpdatePanel ...>
        <ContentTemplate>
            <li id="lione" runat="server">...</li>
            <li id="litwo" runat="server">...</li>
        </ContentTemplate>
        <Triggers>
            ...
        </Triggers>
    </asp:UpdatePanel>
    <li>...</li>
</ol>

It makes sense to me this way, but I guess I'll need to rethink my page layout.

Solution 2

I have encountered the same issue. In my case Page (Table) was not designed properly. Here is the issue details in my scenario:

    <table>
<tr>
<td>
    <asp:Label id="Lb1" runat="server"/>
</td>
</tr>
<asp:UpdatePanel id="UP1" runat="server">
<ContentTemplate>
       <!-- controls in Update Panel-->
</ContentTemplate>
</asp:UpdatePanel>
<tr>
<td>
    <asp:Button id="btn" OnClick="btn_Click" runat="server"/>
</td>
</tr>
</table>

I have changed to

<table>
<tr>
<td>
    <asp:Label id="Lb1" runat="server"/>
</td>
</tr>
**<tr>
<td>**
<asp:UpdatePanel id="UP1" runat="server">
<ContentTemplate>
       <!-- controls in Update Panel-->
</ContentTemplate>
</asp:UpdatePanel>
**</td>
</tr>**
<tr>
<td>
    <asp:Button id="btn" OnClick="btn_Click" runat="server"/>
</td>
</tr>
</table>

Issue resolved moving Update panel in to another table row. So I strongly believe proper screen design should address this type of issues.

Solution 3

had the same error placed the update panel between the tags by mistake instead of the nested tags. That fix did it so i took it from this:

<table>
<tr>
<asp:UpdatePanel runat="Server">
<ContentTemplate>
<td>

    //code here

</td>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</table>

to :

<table>
<tr>
<td>
<asp:UpdatePanel runat="Server">
<ContentTemplate>

    //code here


</ContentTemplate>
</asp:UpdatePanel>
</td>