<div>
Also maybe fix is:<br />
CausesValidation=&quot;false&quot;<br />
<br />
according to:<br />
<a href="http://www.dotnet-developer.de/2008/07/aspnet2005/a-control-is-already-associated-with-the-element/" rel="ugc">http://www.dotnet-developer.de/2008/07/aspnet2005/a-control-is-already-associated-with-the-element/</a>
</div>


Also maybe fix is:
CausesValidation="false"

according to:
http://www.dotnet-developer.de/2008/07/aspnet2005/a-control-is-already-associated-with-the-element/ [http://www.dotnet-developer.de/2008/07/aspnet2005/a-control-is-already-associated-with-the-element/]

<div>
1) Debug script causes errors<br />
2) The live websites are using debug scripts (not release) despite webcongig debug = false <br />
<br />
<a href="http://ajaxcontroltoolkit.codeplex.com/WorkItem/View.aspx?WorkItemId=17952" rel="ugc">http://ajaxcontroltoolkit.codeplex.com/WorkItem/View.aspx?WorkItemId=17952</a>
</div>


1) Debug script causes errors
2) The live websites are using debug scripts (not release) despite webcongig debug = false

http://ajaxcontroltoolkit.codeplex.com/WorkItem/View.aspx?WorkItemId=17952 [http://ajaxcontroltoolkit.codeplex.com/WorkItem/View.aspx?WorkItemId=17952]

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<div class="content wysiwyg-content">
Hi ,<br />
<br />
I am developing a .NET application and testing in IE7.<br />
I have used a Tab Container and built Controls inside each tab panel.<br />
I have also used ModalPopupExtender to show popups.<br />
When I am trying to change tabs and when I close the window, I am getting the following error :<br />
Microsoft JScript runtime error :Sys.InvalidOperationExcep<wbr />tion: Handler was not added through the Sys.UI.DomEvent.addHandler<wbr /> method.<br />
Not sure what the problem is ..<br />
Can anyone help in this regards .<br />
<br />
Thanks !
</div>
</div>


Hi ,

I am developing a .NET application and testing in IE7.
I have used a Tab Container and built Controls inside each tab panel.
I have also used ModalPopupExtender to show popups.
When I am trying to change tabs and when I close the window, I am getting the following error :
Microsoft JScript runtime error :Sys.InvalidOperationException: Handler was not added through the Sys.UI.DomEvent.addHandler method.
Not sure what the problem is ..
Can anyone help in this regards .

Thanks !

Microsoft JScript runtime error :Sys.InvalidOperationException: Handler was not added through the Sys.UI.DomEvent.addHandler method.

The .NET Framework is not specific to any one programming language; rather, it includes a library of functions that allows developers to rapidly build applications. Several supported languages include C#, VB.NET, C++ or ASP.NET.