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The Controls collection cannot be modified because the control contains code blocks Error..

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Ajax

This is a migrated thread and some comments may be shown as answers.

Jason Maronge asked on 25 Apr 2007, 12:11 AM

I am trying to change to the new AjaxManager and AjaxPanel and right off the bat I am getting the following error:

Source:	System.Web
Message:	Exception of type 'System.Web.HttpUnhandledException' was thrown.
Inner Exception:	The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).
Stack Trace:	at System.Web.UI.ControlCollection.AddAt(Int32 index, Control child) at Telerik.Web.UI.RadAjaxControl.MoveUpdatePanel(Control initiator, Control updated) at Telerik.Web.UI.RadAjaxControl.PerformRender() at Telerik.Web.UI.RadAjaxControl.OnPageRender(HtmlTextWriter writer, Control page) at Telerik.Web.UI.RadAjaxControl.RenderPageInAjaxMode(HtmlTextWriter writer, Control page) at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) at System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) at System.Web.UI.Page.Render(HtmlTextWriter writer) at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) at System.Web.UI.Control.RenderControl(HtmlTextWriter writer) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Form:
Query String:
Target Site:	Boolean HandleError(System.Exception)

All i have done is change the radA:RadAjaxPanel to telerik:RadAjaxPanel. I also added the <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %> tag to the top of the page. I also put a ScriptManager on the page. Is there something I missed?

Thanks, Jason

52 Answers, 1 is accepted

answered on 26 Apr 2007, 01:01 PM

I am getting this error too. And I don't have code blocks at all. The following is the code:

                <telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server"> 
                    <asp:Label ID="noAvatarWarn" runat="server" /> 
                    <asp:Image ID="avatar" runat="server" /> 
                    <asp:Image ID="offlineAvatar" runat="server" /> 
                    <asp:Button ID="Button2" runat="server" Text="Button" SkinID="hiddenbutton" /> 
                </telerik:RadAjaxPanel> 

by the way, I originally coded this part with RadAjaxPanel, and everything worked fine.

answered on 27 Apr 2007, 11:45 AM

WebSite.zip

Hi Sam,

I tried to replicate this unfortunately to no avail - it seems that the source of the problem is somewhere else. You can find small demo attached.

Sincerely yours,
Vlad
the telerik team

Instantly find answers to your questions at the new Telerik Support Center

answered on 05 Mar 2008, 05:21 PM

I got my page to run by blocking out the javascript, but now the javascript seems to run after the AJAX runs. I did not have the problem with previous RadAjax. Please advise, this entire page may need to be recoded.

RadAjaxPanel1.ResponseScripts.Add(

string.Format("hideDropDowns();"));

function hideDropDowns()

{

var ddlIDs = document.getElementById('<%= dropDownListIDs.ClientID %>');

var ids = ddlIDs.value.split(',');

for( var i = 0 ; i < ids.length ; i++)

{

if( ids[i] != '')

{

try {

var currentDropDown = document.getElementById(ids[i]);

currentDropDown.style.display =

"none";

currentDropDown.style.visibility =

"hidden";

}

catch(e) {};

}

answered on 06 Mar 2008, 01:17 PM

I blocked out the JavaScript using the RadCodeBlock tags. The page now loads with all the dropdowns visible and then quickly changes to hide them properly. This causes the page to load too wide and then fix itself. Before, the page would just load correctly from the start.

telerik:RadCodeBlock runat="server">

script language="javascript" type="text/javascript">

<!--

function displayDropDown(timeTypeDD, projectDD, sctsDD, otherDD)

{

var ddlIDs = document.getElementById('<%# dropDownListIDs.ClientID %>');

var selectedValue = timeTypeDD.value;

if (selectedValue == 1) {

projectDD.style.display =

"inline";

projectDD.style.visibility =

"visible";

projectDD.focus();

sctsDD.style.display =

"none";

sctsDD.style.visibility =

"hidden";

otherDD.style.display =

"none";

otherDD.style.visibility =

"hidden";

}

else if (selectedValue == 2) {

projectDD.style.display =

"none";

projectDD.style.visibility =

"hidden";

sctsDD.style.display =

"inline";

sctsDD.style.visibility =

"visible";

sctsDD.focus();

otherDD.style.display =

"none";

otherDD.style.visibility =

"hidden";

}

else if (selectedValue == 3) {

projectDD.style.display =

"none";

projectDD.style.visibility =

"hidden";

sctsDD.style.display =

"none";

sctsDD.style.visibility =

"hidden";

otherDD.style.display =

"inline";

otherDD.style.visibility =

"visible";

otherDD.focus();

}

function hideDropDowns()

{

var ddlIDs = document.getElementById('<%= dropDownListIDs.ClientID %>');

var ids = ddlIDs.value.split(',');

for( var i = 0 ; i < ids.length ; i++)

{

if( ids[i] != '')

{

try {

var currentDropDown = document.getElementById(ids[i]);

currentDropDown.style.display =

"none";

currentDropDown.style.visibility =

"hidden";

}

catch(e) {};

}

function focusCategory(categoryDD)

{

categoryDD.focus();

}

-->

script>

telerik:RadCodeBlock>

answered on 06 Mar 2008, 05:25 PM

RadCodeBlock.zip

Hi Allan,

Unfortunately I was not able to reproduce your problem. I am attaching a sample project illustrating my approach to this forum post. Please tell us if we omitted something from your logic - this can lead us to the source of the issue to eliminate it accordingly.

Kind regards,
Iana
the Telerik team

Instantly find answers to your questions at the new Telerik Support Center

answered on 30 Apr 2008, 08:49 PM

I am in the correct thread, just wanted to mention that since the red WARNING pops up here.

ASP.NET AJAX (formerly "Prometheus") is causing me problems. My site worked fine before I upgraded, but now some pages seem unable to load because of the error noted in this thread. Not all of my pages, but most of them. Some pages that have the RadAjaxManager seem to work fine, but others do not. Here is the call stack associated with this error:

    
            [HttpException (0x80004005): The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).]  
        
               System.Web.UI.ControlCollection.AddAt(Int32 index, Control child) +2108046  
        
               Telerik.Web.UI.RadAjaxControl.MoveUpdatePanel(Control initiator, Control updated) +171  
        
               Telerik.Web.UI.RadAjaxControl.PerformRender() +373  
        
               Telerik.Web.UI.RadAjaxControl.OnPageRender(HtmlTextWriter writer, Control page) +1309  
        
               Telerik.Web.UI.RadAjaxControl.RenderPageInAjaxMode(HtmlTextWriter writer, Control page) +152  
        
               System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +98  
        
               System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +20  
        
               System.Web.UI.Page.Render(HtmlTextWriter writer) +26  
        
               System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +25  
        
               System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +121  
        
               System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +22  
        
               System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2558

I find that the "workaround" you posted concerning the RadCodeBlock tag fixes my problem. This is completely unacceptable, as noted by Konstantin Petkov in the post of 1/4/2008 1:31:07 AM below. Konstantin acknowledged the unacceptable nature of this solution in early January, nearly four months ago, and still no solution has been found. This, also, is unacceptable.

I'm finding that my code works fine if I delete RadAjaxManager from the page. That seems like an odd solution for a set of controls that has AJAX in the name.

Should I just go back to the old version of the controls? Why then did I pay the subscription price?

answered on 01 May 2008, 03:50 PM

I was very frustrated yesterday. Today I'm feeling much better, but I have to admit I haven't started working yet. :) Still, sorry about yesterday's rant.

However, I still have some issues with this whole situation. Asking us to move <script> blocks out of the <head> is not an acceptable solution. <script> blocks belong in the <head>, that's how HTML is set up.

Telling us we can't use code blocks (<% %>) in our scripts is not acceptable either. You're saying that your ASP.NET AJAX controls don't support ASP.NET. If that's the case, then you really can't call them ASP.NET controls, can you?

Also, every example of the RadAjaxLoadingPanel I've seen on your site uses code blocks (<%= RadAjaxLoadingPanel.GetWebResourceUrl(Page, "Telerik.Web.UI.Skins.Default.Ajax.loading.gif") %>). If the RadAjaxManager is having trouble with code blocks, why is your RadAjaxLoadingPanel using them? All of your other controls seem to be able to find their images in the Telerik.dll file without using code blocks. Why does the RadAjaxLoadingPanel seem to be unable to do this? And do I need to wrap that code block in <RadCodeBlock> tags?

At this point I can get by with the <RadCodeBlock> tags in my code. I don't use many code blocks, since I try to follow the ASP.NET programming model of separating UI from business logic. Still, ASP.NET code blocks are an integral part of ASP.NET programming, as Telerik has demonstrated in the use of them in the RadAjaxLoadingPanel. I do hope that this issue gets resolved soon.

Thanks -
Brad

answered on 07 May 2008, 02:45 PM

Hello, I am running into this same problem as well. I would also like to express the same dissatisfaction that the others in this forum have expressed. It was a very bad decision on the telerik developers part to force your customers to sourround all instances of <%= %> with the RadCodeBlock. It should have been realized that this type of requirement would cause too many problems and too big of an inconvenience for customers with large projects who wants to upgrade. It's an extra process to remember and keep track of. The nature of asp.net lends itself to nested pages, objects, and reusable controls. I have a feeling I will constantly be running into this error and subsequently having to search each layer of nested pages and web controls for <%=%> tags, what a pain! Plus it clutters up the aspx file even more.

</rant>

answered on 30 Jun 2008, 11:23 AM

Sorry if I misunderstood. I'd like to re-illustrate my problem here:
1. I use the Telerik controls within a DotNetNuke module. DNN uses script blocks which I don't want to change.
2. I don't use any code or script blocks myself (just Telerik controls like RadGrid, RadComboBox)
3. Version 2007 Q3 worked fine
4. Version 2008 Q1 gives me the 'The Controls collection cannot be modified...' error

This is the issue I was complaining about. At first, I understood that I needed to encapsulate the script DNN script blocks with RadScriptBlock, but now you say I 'don't have to change anything in the third-party control scripts'?
Please inform me about any misinterpretations and what I should do to get rid of this error.

Thanks,
Willem

answered on 22 Apr 2013, 03:00 PM

Ok, here is a workaround. This is what I did from a Website created in ASP.NET 4.5 using the standard built-in web template.

Basically, the built-in template has a header like this:

<head runat="server">

<title ><%: Page.Title %> - My Site</title>

<meta charset="utf-8" />

<meta name="viewport" content="width=device-width" />

<asp:PlaceHolder runat="server">

<%: Scripts.Render("~/bundles/modernizr") %>

</asp:PlaceHolder>

<webopt:BundleReference runat="server" Path="~/Content/css" />

<link href="~/favicon.ico" rel="shortcut icon" type="image/x-icon" />

<asp:ContentPlaceHolder runat="server" ID="HeadContent" />

</head>

So, you've added either a RadAjaxManager or RadAjaxPanel on your MasterPage or Form. And you get the same error mentioned in this Thread. So the recommendation is to remove the "runat=server" from your head tag which then breaks the whole site and causes all sorts of redesign, meetings, pulling of hair, nashing of teeth, etc. Or, you implement this horrendous solution of wrapping RadCodeBlocks around everything and then you head tag looks like this:

<head runat="server">

<telerik:RadCodeBlock runat="server">

<title><%: Page.Title %> - My Site</title>

</telerik:RadCodeBlock>

<meta charset="utf-8" />

<meta name="viewport" content="width=device-width" />

<telerik:RadCodeBlock runat="server">

<asp:PlaceHolder runat="server">

<%: Scripts.Render("~/bundles/modernizr") %>

</asp:PlaceHolder>

</telerik:RadCodeBlock>

<telerik:RadCodeBlock runat="server">

<webopt:BundleReference runat="server" Path="~/Content/css" />

</telerik:RadCodeBlock>

<link href="~/favicon.ico" rel="shortcut icon" type="image/x-icon" />

<asp:ContentPlaceHolder runat="server" ID="HeadContent" />

</head>

So then you realize you have to retrain all developers to NEVER use any standard built-in ASP.NET syntax such as "<%:" or "<%=", etc. Then you realize, this doesn't make any sense, and you say to yourself: "I noticed that the placeholder control had a "runat=server" and without wrapping that control in a RadCodeBlock, everything worked just fine!".

Ahh, so now the solution presents itself. All we need are server controls wrapping the elements giving us this problem! But, I don't want to wrap my "title" and all my "H1-H6" tags with asp:Panel controls either! So, here it is, the solution to all this mess...
simply set your elements to run from the server (ex. title runat='server').

And finally, the head tag which works with RadAjax!

<head runat="server">

<title runat="server"><%: Page.Title %> - My Site</title>

<meta charset="utf-8" />

<meta name="viewport" content="width=device-width" />

<asp:PlaceHolder runat="server">

<%: Scripts.Render("~/bundles/modernizr") %>

</asp:PlaceHolder>

<webopt:BundleReference runat="server" Path="~/Content/css" />

<link href="~/favicon.ico" rel="shortcut icon" type="image/x-icon" />

<asp:ContentPlaceHolder runat="server" ID="HeadContent" />

</head>

And viola! No RadCodeBlocks!!!

Now, this may not work in all situations, but it has saved me from over-complicating the simplest things in my site.