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Rick Strahl's Web Log

Wind, waves, code and everything in between...
ASP.NET • C# • HTML5 • JavaScript • AngularJs

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).


Bummer. I've been mucking around with some more custom databinding that integrates validation into the databinding process. One of the things the control does is automatically add 'notification' icons or error text to the page. The idea is this:

 

  • Control(s) unbind
  • If there are binding errors an Icon or Message is injected into the Control Collection

 

Basically the code looks something like this:

public bool AddBindingError(string ErrorMessage, wwDataBindingItem BindingItem)

{

    // *** Associated control found - add icon and link id

    if (BindingItem.ControlInstance != null)

        this.BindingErrors.Add(new BindingError(ErrorMessage, BindingItem.ControlInstance.ClientID));

    else

    {

        // *** Just set the error message

        this.BindingErrors.Add(new BindingError(ErrorMessage) );

        return false;

    }

 

    BindingItem.BindingErrorMessage = ErrorMessage;

 

    // *** Insert the error text/icon as a literal

    if (this.ShowBindingErrorsOnControls && BindingItem.ControlInstance != null)

    {

        LiteralControl Literal = new LiteralControl(this.GetBindingErrorMessageHtml(BindingItem));

        int CtlIdx = BindingItem.ControlInstance.Parent.Controls.IndexOf(BindingItem.ControlInstance);

        try

        {

            // *** Can't add controls to the Control collection if <%= %> tags are on the page

            BindingItem.ControlInstance.Parent.Controls.AddAt(CtlIdx + 1, Literal);

        }

        catch {;}

    }

 

    return true;

}

 

And it works beautifully in most situations. The literal control creates markup that loads the appropriate image and adds the error text (if configured that way).

 

This all works great until you happen to have some script markup on the page using. For example if the page contains something as simple as this:

 

<%= DateTime.Now    %>

 

The Controls.AddAt() call will fail with:

 

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

 

Now I feel like a complete schmuck to never have run into this before. That's one hell of an assumption to miss about ASP.NET it seems. I have tons of pages where there's <%= %> markup on it. Especially in script code to get the appropariate ClientID:

 

<%= this.txtCompany.ClientID %>

 

Luckily there's a workaround for code like this by using DataBinding expressions instead:

 

<%# this.txtCompany.ClientID %>

 

This works fine for simple expressions. The difference here is that <%= %> expressions are embedded into the ASP.NET output as part of the generated Parse Tree class, whereas the <%# %> expressions are embedded at runtime.

 

Another workaround is to force any script code into the content of a server control and remove it from the Page class or the Content container that you're adding controls to.

 

   <div runat="server">

    <script type="text/javascript">

      function ShowCreditCard()

      {

         var IsPayPal = false;

         for(x=0; x<4; x++ )

         {

                var ctl = $("<%= this.txtCCType.ClientID %>_" + x.toString());

                if (ctl == null)

                     break;

               

                if (ctl.value == "PP" && ctl.checked)

                {

                     IsPayPal = true;

                     break;

                }

         }

        

         var loCC = $("<%= this.trCreditCard.ClientID %>");

         if (loCC == null)

            return;

         var loCC2 = $("<%= this.trCreditCardExpiration.ClientID %>");

 

         if (IsPayPal)

         {

            loCC.style.display = "none";

            loCC2.style.display = "none";

         }           

         else

         {

            loCC.style.display = "";

            loCC2.style.display = "";

         }

      }

</script>

</div>

 

This works as well, although this is also pretty ugly. In my case this is probably the easier solution though, because most of my markup expressions are doing exactly what's happening above: Embedding ClientScript Ids into JavaScript.

 

I still don't see why the control collection can't be modified if there are <% %> blocks on the page. Those blocks are just turned into Response.Write() commands, or raw code blocks. I don't see how this affects the Controls collection that would require this sort of error.

 

In my situation here I was able to get by just switching to <%# %> or wrapping sections with a server tag. Even if that's not an option the above code captures the error and goes on. This means the warning icons don't show up, but the rest of the error handling showing the summary and error control linking etc. all still works.

 

Can anybody think of another more reliable way to inject markup into the page dynamically from outside of the control rendering? In a previous rev of my databinding tools I had custom controls and I simply took over post rendering which was reliable. But this is not so easily done externally… I can think of possibly hooking up the Render method and calling back into my custom control, but man does that seem ugly.

 

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Rick Strahl's WebLog
May 28, 2006

# Reliably adding Controls or Markup before or after an ASP.NET Control?

Expanding on yesterday's problem with markup script and using Control.Control.Add() I'm trying to find some way to override rendering of a control, from an external control (an Extender in this case). Here are some thoughts, but unfortunately no solutions...

Johan Olofsson
May 30, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %&gt;).

Hi Rick!

If you can live with adding a PlaceHolder control to
your aspx-files, then you can modifiy its (the placeholders)
control collection.

Thanks for an interesting blog,
Johan Olofsson

Rick Strahl
May 30, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %&gt;).

Johan, yes any control container would work actually, but this being a generic control using any sort of specific layout doesn't work.

Milan Negovan
May 30, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %&gt;).

Deja vu, Rick: I was banging my head against the wall over this just the other day:

http://www.aspnetresources.com/blog/code_blocks_inside_master_pages_cause_trouble.aspx

Dennis
June 20, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %&gt;).

Dude, you are the man. I can not tell you how many times I have had a problem (like this one), done a google search and you had the answer. Thanks for sharing your wisdom!

Rick Strahl's WebLog
June 20, 2006

# Working around Controls.Add() and

A while back I had lamented some issues with Controls.Add() when script tags where on the page. This gets in the way of generic controls that need to dynamically add content to a page. After some thought I decided that injecting the markup with client side JavaScript code generated from the control would do the trick.

vikram2101
June 21, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %&gt;).

thanks. you saved me alot of time.

Rick Strahl's WebLog
June 23, 2006

# Adding Rendering with SetRenderMethodDelegate() - aeh, sort of

I ran into SetRenderMethodDelegate today and was thinking it'd be very useful for injecting HTML into a control. Unfortunately it turns out that the delegate is not fired on all controls as there's a dependency on base.Render() calls which apparently are not made by all controls even the stock controls.

Mano
July 18, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. &lt;% ... %&gt;).

Thanks alot man! I've been pulling my hair over this...

Tips & Tricks
October 07, 2006

# Tips & Tricks: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).


Jeremy Wadsworth
October 17, 2006

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Crap, every time I've come across this error, I've managed to find another way to accomplish whatever I was trying to do. I came across the error again today, and decided to Google it. I have no idea why I didn't Google it before. Thanks for the solution. Great blog as well, this isn't the first time a search engine has brought me to your site.

Rick Strahl
October 17, 2006

# More info on why the error occurs

I have more detailed information on exactly why this error occurs as part of the ASP.NET page rendering here:

http://west-wind.com/WebLog/posts/6148.aspx

Tips & Tricks
November 24, 2006

# Tips & Tricks: 09/01/2006 - 10/01/2006


Tom Holder
January 05, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I've experienced the same issue with the .NET RSS Toolkit (which is great - despite this).

I had some code like the following in my head to link a CSS:


The RssHyperLink control was causing it to break because it's trying to add a literal control in to the head for the link.

I solved it by putting in a PlaceHolder property and then putting a placeholder in to my head and then finding all of the rsshyperlink controls and passing it along.

There has to be a better way, but it's fixed it for me.

Tom Holder
January 05, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Sorry, missed out the code throwing causing the error:

<link rel="stylesheet" type="text/css" href="<%=ResolveUrl("~/css/global.css")%>" media="screen" />

Rick Strahl
January 05, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Actually a placeholder control (or a label or literal) all work and that's just fine. But it's less efficient (controls have a lot of overhead compared to eval expressions) and IMHO for something a heck of a lot less maintainable for such a simple thing.

Whirlpool.net.au
February 11, 2007

# Code Blocks vs. Controls Collection - ASP - Coding & Web - Whirlpool Broadband Forums


Stosh
March 27, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

On my page, I was able to fix an instance of this error by moving script out of the <head> tag and into the <form> tag.

Alexander
April 02, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

you can just move the script out of the head block to the form block. that works fine.

Web Forms
April 16, 2007

# ASP.NET Forums - Code blocks usage


ASP.NET Forums
May 28, 2007

# asp:image question - ASP.NET Forums


ASP.NET Forums
June 03, 2007

# Code blocks usage - ASP.NET Forums


almir
June 11, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

it worked,
I love you

Sam
August 22, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Moving the script with the embedded <% %> tags from the head to the form tag worked for me too. Great article - thanks.

Mandy
September 05, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks Rick, this was really helpful!

Travich
October 05, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

This happens when I add the ajax calenderExtender to my DataGrid. Funny thing is, that I didn't add any script... Now I can't figure out why this is happening. Grrr...


<asp:ImageButton runat="Server" ID="calImage" ImageUrl="/images/Calendar.gif" AlternateText="Click to show calendar" /><br />
<ajaxToolkit:CalendarExtender ID="calendarButtonExtender" runat="server" TargetControlID="txtTestedDate"
PopupButtonID="calImage" />

Michael KOcher
October 12, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks a bunch!

Nitin Gupta
October 24, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

That saved me a lot of time and frustration.........

Thanks!

Wil
October 30, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Moving the script with the embedded <% %> tags from the head to the form tag worked for me too.

Josh
November 01, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Worked perfectly, thanks for the heads up about this. You da man!

Michael Clark
November 07, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I've just had the same issue, requiring a bit of javascript inside a control to know the id of a control... my solution was in JS to add:-

var moo = "<asp:Literal runat="server" id="litMonkey"></asp:Literal>";


then in the code-behind...

litMonkey.Text = objMonkey.ClientID

Timmus
December 06, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thank you, sir. I am using multiple AJAX ModalPopupExtender controls and the user controls depend on the pageLoad event. I moved all the usercontrol javascript code to the host page to support a number of controls (this is a CRM app). Unfortunately I encountered the above mentioned error. I almost cried :). Thank you for posting your findings as it has been very helpful.

Timmus

Ganesh
December 13, 2007

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Great!!!It worked out and no erros received....Thanks for sharing

Alex
February 20, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Wow. Thanks for sharing.
Your blog is a gem!!! Keep up :)

Dan
February 26, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I had a similar problem to the GridView comment above, but it happened when I added the AJAX Calendar Control Extender to a Repeater control.

The problem went away once I removed the <%# %> from the javascript in the header. I would not call this a 'fix' though. I was able to work around the absence of the code block in the script this time, but may not be able to in the future.

I have also managed to add some key script code dynamically in server-side code (for instance, creating variables and all the script, but add assignments to those variables server-side)

Good blog!

Dan Sharpe
February 28, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I found two more reasons this error can occur while upgrading to VS 2008 Ajax using the AjaxControlToolKit for .net 2.0 and 3.5

When the MaskedEditExtender/CalendarExtender is used, a <LINK ...> tag to a stylesheet will result in this error. One workaround is to move the CSS file to a theme folder and add a reference to the theme in the web.config file <pages theme="themeName">. Each page needs to have the "<head>" tag replaced with "<head runat="server"> and any "<LINK ...>" tags removed.

Also, comments in the HEAD section can cause this problem. Take the following javascript example:

function DelLot()
{ // Called to delete the order.
// true means it was deleted -- false means it was not.
// return(window.showModalDialog("AskDelete.aspx?MODE=D&EBID=<%=nID%>", null,"dialogwidth:600px;dialogHeight:400px;help:no;resizable:no;scroll:no;status:no"));
}

Temporarily commenting out this javascript code, or perhaps anything in the head section, will still result in the same error when the page init event is fired. If the code block is needed, the javascript can be moved from the head section to the body section. Otherwise, you need to remove the code block completely, because commenting it out is not enough to resolve this error.

Good luck, Best, db.netDan

Rima
March 10, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks Dan,

Your comment has resolved my problem. I also had a code which was commented. i have removed it and problem is solved.

Thanks again.

jay
May 28, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks Rick !!!!

I solved the problem by placing a PlaceHolder and moving the script block from head to form tag...

You saved my day!!!!

Mike
June 04, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Neither of the methods described in the article above work for me. There must be some cases where this still is a problem. I have tried:

1) Switching to <%# ... %> tags, I just get no output from these at all, no good.
2) Wrapping <script> block in a <div runat="server"> block, no effect.
3) My script is already in the <FORM> tag, so nothing I can try there.

My code is in a user control, not sure if that has anything to do with it or not. NONE of the solutions presented on the web that others are claiming are working are working for me. This pisses me off.

Rick Strahl
June 04, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

<%# %> tags require databinding. You'll need to bind in order for that to work.

Wrapping in a <div runat="server"> or a asp:PlaceHolder control should always work to ensure that <%= %> tags are isolated from the parent container. The key is to have an independent container that contains nothing else.

<script> is not affected at all by any of these - this only concerns <% %> tags.

Jeremy
June 10, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Oh you rock! I was losing hope as at first the solutions weren't working. Then I read that last blurb about the server div and it finally clicked, and worked! Woo hoo! Thanks for this!

Prashanth
August 06, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Hey guys this blog helped me a lot u guys rocks...

Aaron
August 13, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I also moved the script out of the head to the body and it worked.

sohan kanojia
August 20, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

gud work it's really work thanks a ton.

Larry Pauley
September 12, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I dont know if anyone else found this, but if you specify your script in the following manner, the problem will go away. Make sure you include the begin and end HTML commented out lines.

<script type='text/javascript'>
<!--
(javacript goes here)
//-->
</script>

Rick Strahl
September 15, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

@Larry - I don't think that makes a difference. It's the <%= %> tags that cause the problem when embedded in the script block. Haven't tried it but I'm pretty sure that it would still fail because we're talking about server side tags here.

Theone84
September 27, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Yes it Worked Alexander ,Thanks

Patrick Farrell
October 01, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks Rick. I just ran into same thing. Betcha it's my Java background.

TurtleWax
October 21, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Rick, the "div/runat=server" trick seriously saved me. Thanks...
Your post is now 2 years old, so assuming your opinions hasn't changed, what were your concerns about this approach?


<div runat="server">
<script type="text/javascript">
function ShowCreditCard()
{
}
</script>
</div>

Issa Qandil
October 23, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

This is really helpful thanks guys ;)

Lisa
October 23, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks for posting this! You saved my bacon.

Vladimir
October 30, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Hi Rick,

Just run into the same ugly problem. My workaround is to use ClientScriptManager (or in my case its AJAX'ed version, ScriptManager class, from Page_PreRender (where we have a correct ClientID):

if (!sm.IsInAsyncPostBack)
{
ScriptManager.RegisterClientScriptBlock (upDummy, upDummy.GetType (), "startup", string.Format ("var favNameClientId='{0}';", edFavName.ClientID), true);
}

This way it will embed in resulting HTML the script statement:
<script type="text/javascript">
//<![CDATA[
var favNameClientId='edFavName';//]]>
</script>

Note that this statement will be inserted at the very beginning of <body>, actually right after <script src="..."></script> blocks, so it safely can be used whenever below this point from javascripts at this page.

Also note, that this value will remain unchanged while async postbacks, so you don't need to call this method during later async postbacks, but only that's why it's wrapped in 'if'

Cheers,
Vladimir

Chris
October 30, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I've tried a lot of these suggestions and nothing seems to work. I am using the <% %> tags to get resource variables for internationalization of an application. One of the tags is being passed into a javascript function on a postback. I've tried using the #, instead of =, but then the link disappears. I've also attempted to move the javascript into the body of the page, but that doesn't work either. I am using Master pages. Any help would be greatly appreciated. Thank you.

Chris

Fortune Ngwenya
November 17, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

you're the man!

Atef Elkabani
November 19, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I have faced the same problem.

that because you can't add control

"Me.Master.FindControl("form1").Controls.Add(ctrl)"

to a form that have block (<% ... %>)

The best solution is to remove that block and try other solution
like add server side control

e.g

<a runat="server" id="lnkHome">

lnkHome.href= session("linkTitle") 'vb Code

instead of

<a href="index.aspx"><%= session("linkTitle") %> </a>

Nicolas
November 25, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thank you people!!!

<div runat="server">
<script type="text/javascript" language="javascript">
...
</script>
</div>


works like a charm!!

Mike
December 07, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Yes, thank you!

I wish I had come across this page two years ago!

DotNetKicks.com
December 18, 2008

# The Controls collection cannot be modified because the control contain

You've been kicked (a good thing) - Trackback from DotNetKicks.com

proxy
December 23, 2008

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

<div runat="server">...saved my ass!!

Thanks,
:)

Sudheer
January 05, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thank you ... :)

me
January 13, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

thanks, using the <div runat=server... then a script tag helped me... really doesn't seem so intuitive... thanks!

DD
February 03, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Hey there! I seriously need help with this one. I am trying to use the Calendar Tool and came across the said error.

I tried the <%#> <%> solution but it didn't work for me (or maybe I'm doing it wrong).

My MasterPage does not have any <%><%> code but the content page does have a couple.

Here's a snippet from the content page.
<%@ Page Title="" Language="VB" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="page.aspx.vb" Inherits="Dashboards_page" %>
<%@ Register assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagprefix="cc1" %>

Any ideas? Thanks in advance.

Roch
March 01, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

<div runat=server> Didnt help me.

But, I moved my JS code from <head> to the end of the <body>, and it worked fine!

Rick Strahl
March 01, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

@Roch - a Div tag in the header is not legal, so that's why that probably didn't work. That or because your head tag didn't have a runat="server" in it. The trick is simply to get a server control to wrap script to force the container into its own logical generated code unit.

Faredoon
March 02, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

The <div> solution: superb.

Raja
March 28, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

The DIV tag solution is working fine.

Robert Werner
April 24, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Rick, your piece and that of several others eventually helped me find a solution.

After a lot of research, I've found a programmatic and non-programmatic way to accomplish this. You can read it here: http://mwtech.blogspot.com/2009/04/2-ways-to-load-jquery-from-aspnet.html

I hope it helps out your many readers!

# The Controls collection cannot be modified because the control contains code blocks (i.e. <% … %> ).

I am pretty sure that any web developer would hate an exception that is hard to catch. One of those is

Nuno Santos
June 27, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

First of all sorry my "bad" English.
I try to have a asp:datalist with a calendar extender on edit template, but every time I run the code and put the asp:datalist in edit mode I get the same error (The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>)).
thks
NS

Ahmed Assem
August 04, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

You can try removing the runat="server" from the head tag. this worked for me

choukei
August 05, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

The same error was displayed.

and after a long time's work .

i only put the js out of the <head></head>,but between <head> and <body>.

it is works well.

My english is a little bad.

hoho~~

rashmi
August 14, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Nice article was able to find the root cause and fixed it using
http://www.aspnetresources.com/blog/code_blocks_inside_master_pages_cause_trouble.aspx

Thanks for the details and everyone's input

Abdulla AbdelHaq Blog
September 16, 2009

# How to fix this .. The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Sometimes when you write inline code inside Javascript tag or inside style sheet tag within the header

karthick
October 04, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

i too have solved this problem by removing script section from head tag to inside the body tag

bob
October 30, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).


venkat
November 10, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

div runat=server is working great, thank u very much for ur comments guys

Jake
December 08, 2009

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Rick Strahl! Thanks again for the great tip!

I used WWWC for WFP from 2002-2005 and reminisce pretty fondly over it. We were using it to make AJAX-style callbacks from Flash...

jon
January 08, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

THANK YOU!!!!! The Data bindinng # worked !!!
THANKS FOR PUTTING THIS ON A BLOG!!!!!!

Om Shanker Mishra
February 06, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks a lot! Its really what I needed.

Akshaya
March 31, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

thank u so much... i have been struggling on this from past 15 days... its resolved today.

Doug Den Hoed
April 02, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Splendid! Thank you Rick. I had to read it a couple of times, but found your solution right away and used it to fix my project in less than an hour.

For future victims, what caused the error in my case was adding a Theme for the first time to my VS2008 C# project. Replacing each <% %> with <# %> in my Default.Master got me past the error and showed some of the Theme...but it was ugly. In the end, I went back to <% %> everwhere, and simply added a <div runat=server> around each of my three asp:contentplaceholder controls since each "helpfully" comes with a generated description of each in front that is wrapped with...you guessed it...<% %> symbols to mark them as comments.

Regards,
Doug

james
May 06, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

thanks heaps man :)

Kishore Kumar Nethala
May 18, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Move the javascript <script> tag to the bottom of the page It Works !!..

Vin
June 22, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Just replace <%= by <%# and it will work

ITalez
June 23, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I can confirm that moving the javascript with <% %> tags from the head to the form tag fixes this error

http://italez.wordpress.com

Elton Tadeu
July 13, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Valeu brother...
comigo funcionou usando o <div runat="server"><%= ... %></div>

Manaf
August 03, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks a million people , i thought it will never work ,
the Div runat Server worked like a charm , thanks God

<div runat="server">
<script type="text/javascript">
....
<% =CSharpFunction() %>
</script>
</div>

Manaf

KiS
November 10, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Hi, thanks for the tip guys.

Yes, moving the javascript with <% %> tags from the head into the form tag works for me as well!

Cheers!

Syed Shomaail Jafri
December 04, 2010

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

gr8 work
thanks

Anup Dharia
January 13, 2011

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks a million people , i also thought it will never work ,
the Div runat Server really worked like a charm.

<div runat="server">
<script type="text/javascript">
....
<% =CSharpFunction() %>
</script>
</div>

Dyamanagowda
June 24, 2011

# re: The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

Thanks a Lot Rick . I removed my code from head block and put all my scripts inside th body under div tag as u mentioned. Its working fine.


Regards,
Dyamanagowda
 


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