blocks|key|279856|text|很难确定，因为您没有包含太多细节，但我认为发生的情况是在您的Page.Header中有<%25+...+%25>代码块(它引用<head+runat="server">+-可能在母版页中)。因此，当您尝试将项添加到该控件的Controls集合时，会在此问题的标题中看到错误信息。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|279857|如果我是对的，那么解决方法是在<%25+...+%25>代码块周围包装一个<asp:placeholder+runat="server">标记。这使代码块成为占位符控件的子级，而不是Page.Header控件的直接子级，但它根本不会更改呈现的输出。既然代码块不是Page.Header的直接子代，您就可以将内容添加到头的controls集合中而不会出错。|279858|同样，在某个地方有一个代码块，否则您不会看到这个错误。如果它不在aspx页面中，那么我首先要查看的是aspx顶部的MasterPageFile属性所引用的文件。|279859|entityMap^0|U|B|17|9|1N|L|0|F|9|X|W|2F|B|3J|B|0|1L|E|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|K|$]]

It's hard to tell for sure because you haven't included many details, but I think what is going on is that there are <code>&lt;% ... %&gt;</code> code blocks inside your <code>Page.Header</code> (which is referring to <code>&lt;head runat="server"&gt;</code> - possibly in a master page). Therefore, when you try to add an item to the Controls collection of that control, you get the error message in the title of this question.

If I'm right, then the workaround is to wrap a <code>&lt;asp:placeholder runat="server"&gt;</code> tag around the <code>&lt;% ... %&gt;</code> code block. This makes the code block a child of the Placeholder control, instead of being a direct child of the <code>Page.Header</code> control, but it doesn't change the rendered output at all. Now that the code block is not a direct child of <code>Page.Header</code> you can add things to the header's controls collection without error.

Again, there is a code block somewhere or you wouldn't be seeing this error. If it's not in your aspx page, then the first place I would look is the file referenced by the <code>MasterPageFile</code> attribute at the top of your aspx.

blocks|key|3203213|text|以防万一，如果你正在使用Telerik组件，并且你的javascript中有一个<%25=的引用……%25>然后用RadScriptBlock包装脚本标记。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3203214|+<telerik:RadScriptBlock+ID="radSript1"+runat="server">
+++<script+type="text/javascript">
++++++++//Your+javascript
+++</script>
</telerik>|code-block|syntax|javascript|3203215|致敬？？|3203216|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Just in case if you are using Telerik components and you have a reference in your javascript with &lt;%= .... %> then wrap your script tag with a RadScriptBlock. 

<pre><code> &lt;telerik:RadScriptBlock ID="radSript1" runat="server"&gt;
 &lt;script type="text/javascript"&gt;
 //Your javascript
 &lt;/script&gt;
&lt;/telerik&gt;
</code></pre>

Regards Örvar

blocks|key|278024|text|请访问"The+Controls+collection+cannot+be+modified+because+the+control+contains+code+blocks"查看解决方案|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|278025|accepted+solution+on+the+other+question适用于我--将<%25=的实例更改为<%25#，它将代码块从Response.Write转换为求值块，这不受相同限制的限制。|style|CODE|278026|在这种情况下，就像accepted+solution+here建议的那样，您应该将控件添加到母版页ContentPlaceHolder元素之外的其他元素中，即建议的asp:Placeholder控件。|278027|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/778952/the-controls-collection-cannot-be-modified-because-the-control-contains-code-bl|1|https://stackoverflow.com/a/1176779/1037948|2|https://stackoverflow.com/a/4995628/1037948^0|3|2D|0|0|1A|3|1J|3|1T|E|0|13|1|0|2A|F|9|M|2|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|6|7|Z|8|@$A|10|B|11|F|G]|$A|12|B|13|F|G]|$A|14|B|15|F|G]]|9|@$A|16|B|17|1|18]]|C|$]]|$1|H|3|I|5|6|7|19|8|@$A|1A|B|1B|F|G]]|9|@$A|1C|B|1D|1|1E]]|C|$]]|$1|J|3|-4|5|6|7|1F|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]|R|$5|M|N|O|C|$P|S]]|T|$5|M|N|O|C|$P|U]]]]

Check out the solutions at <a href="https://stackoverflow.com/questions/778952/the-controls-collection-cannot-be-modified-because-the-control-contains-code-bl">&quot;The Controls collection cannot be modified because the control contains code blocks&quot;</a>

The <a href="https://stackoverflow.com/a/1176779/1037948">accepted solution on the other question</a> worked for me -- change instances of <code>&lt;%=</code> to <code>&lt;%#</code>, which converts the code block from <code>Response.Write</code> to an evaluation block, which isn't restricted by the same limitations.

In this case though, like the <a href="https://stackoverflow.com/a/4995628/1037948">accepted solution here</a> suggests, you should add the controls to something other than a masterpage ContentPlaceHolder element, namely the <code>asp:Placeholder</code> control suggested.

blocks|key|3203296|text|我也遇到过同样的问题，我用这种方法解决了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3203297|而不是将元添加到导致与您相同的错误的当前页眉：|3203298|Page.Header.Controls.Add(meta);|code-block|syntax|javascript|3203299|我使用了下面的代码：|3203300|+Master.FindControl("YourHeadContentPlaceHolder").Controls.Add(meta);|3203301|它就像护身符一样起作用。|3203302|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I have had the same issue that I solved this way:

Instead of adding the meta to the current page header that caused the same error as you had:

<pre><code>Page.Header.Controls.Add(meta);
</code></pre>

I used this instead:

<pre><code> Master.FindControl("YourHeadContentPlaceHolder").Controls.Add(meta);
</code></pre>

and it works like a charm.

blocks|key|278072|text|这并不能真正解决你的问题，但它是一个重要的替代方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|278073|如果您想将自定义html添加到页面的开头(在<body>元素中)，您可以使用Page.ClientScript.RegisterClientScriptBlock()。|offset|length|style|CODE|278074|虽然这个方法叫"script"，但你可以添加任意字符串，包括html。|278075|entityMap^0|0|M|6|12|19|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]|$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|K|$]]

Not really solve your question but it's an important alternative.

If you want to add custom html to the beginning of the page (inside <code>&lt;body&gt;</code> element), you may use <code>Page.ClientScript.RegisterClientScriptBlock()</code>.

Although the method is called "script", but you can add arbitary string, including html.

blocks|key|3203366|text|对于那些使用Ovar提到的Telerik的用户，请确保将javascript封装在|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3203367|+<telerik:RadScriptBlock+ID="radSript1"+runat="server">
+++<script+type="text/javascript">
++++++++//Your+javascript
+++</script>
</telerik>|code-block|syntax|javascript|3203368|由于Telerik在查找元素时无法识别<%25#+%25>，并且如果您的<%25=代码未包装，%25>将给您一个错误。|3203369|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

For those using Telerik as mentioned by Ovar, make sure you wrap your javascript in 

<pre><code> &lt;telerik:RadScriptBlock ID="radSript1" runat="server"&gt;
 &lt;script type="text/javascript"&gt;
 //Your javascript
 &lt;/script&gt;
&lt;/telerik&gt;
</code></pre>

Since Telerik doesn't recognize &lt;%# %> when looking for an element and &lt;%= %> will give you an error if your javascript code isn't wrapped.

blocks|key|2989797|text|在ContentPlaceholder中，将占位符control.For示例放在下面|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2989798|<asp:Content+ID="header"+ContentPlaceHolderID="head"+runat="server">
+++++++<asp:PlaceHolder+ID="metatags"+runat="server">
++++++++</asp:PlaceHolder>
</asp:Content>|code-block|syntax|javascript|2989799|代码隐藏：|2989800|HtmlMeta+hm1+=+new+HtmlMeta();
hm1.Name+=+"Description";
hm1.Content+=+"Content+here";
metatags.Controls.Add(hm1);|2989801|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Inside ContentPlaceholder, put the placeholder control.For Example like this,

<pre><code>&lt;asp:Content ID="header" ContentPlaceHolderID="head" runat="server"&gt;
 &lt;asp:PlaceHolder ID="metatags" runat="server"&gt;
 &lt;/asp:PlaceHolder&gt;
&lt;/asp:Content&gt;
</code></pre>

Code Behind:

<pre><code>HtmlMeta hm1 = new HtmlMeta();
hm1.Name = "Description";
hm1.Content = "Content here";
metatags.Controls.Add(hm1);
</code></pre>

I am trying to create dynamic meta tags in C# but it gives the following error:

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

This is the code I added:

<pre><code>HtmlMeta meta = new HtmlMeta();
meta.Name = "keywords";
meta.Content = "book,paper";
Page.Header.Controls.Add(meta);
</code></pre>

Thank you very much.

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

我试图在C#中创建动态元标签，但它给出了以下错误：无法修改Controls集合，因为该控件包含代码块(即<% ... %>)这是我添加的代码：HtmlMeta meta = new HtmlMeta();meta.Name = "keywords";meta.Content = "book,paper";Page.He...

问无法修改Controls集合，因为该控件包含代码块(即<% ... %>)
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