ASP.NET AJAX provides new APIs for registering script with the ScriptManager.  Using these APIs allows controls to work well with partial rendering.  Without them, controls placed inside an UpdatePanel won't work as expected. In previous CTP releases of ASP.NET AJAX, we had a set of validator controls that derived from the v2.0 controls and used the new APIs. This made them work well with ASP.NET AJAX. WindowsUpdate will soon include a version of System.Web that can take advantage of the new APIs.  So the new controls which would have been redundant have been removed.  However, the update isn't available yet and ASP.NET AJAX has been released.  So, in the short-term, the source code for a set of custom validator controls that work with partial rendering is available as an attachment to this post or on my blog http://blogs.msdn.com/mattgi/attachment/1516974.ashx

The .zip file includes a solution and .csproj file as well as the compiled DLL.  Just put the DLL in the /bin directory of your application and include the following <tagMapping section in the pages section of the web.config.

      <tagMapping>
        <add tagType="System.Web.UI.WebControls.CompareValidator"           mappedTagType="Sample.Web.UI.Compatibility.CompareValidator, Validators, Version=1.0.0.0"/>
        <add tagType="System.Web.UI.WebControls.CustomValidator"            mappedTagType="Sample.Web.UI.Compatibility.CustomValidator, Validators, Version=1.0.0.0"/>
        <add tagType="System.Web.UI.WebControls.RangeValidator"             mappedTagType="Sample.Web.UI.Compatibility.RangeValidator, Validators, Version=1.0.0.0"/>
        <add tagType="System.Web.UI.WebControls.RegularExpressionValidator" mappedTagType="Sample.Web.UI.Compatibility.RegularExpressionValidator, Validators, Version=1.0.0.0"/>
        <add tagType="System.Web.UI.WebControls.RequiredFieldValidator"     mappedTagType="Sample.Web.UI.Compatibility.RequiredFieldValidator, Validators, Version=1.0.0.0"/>
        <add tagType="System.Web.UI.WebControls.ValidationSummary"          mappedTagType="Sample.Web.UI.Compatibility.ValidationSummary, Validators, Version=1.0.0.0"/>
      </tagMapping>

http://blogs.msdn.com/mattgi/archive/2007/01/23/asp-net-ajax-validators.aspx

Hi

I have used the same concept but it shows err like

Unrecognized configuration section system.web/tagMapping.

Can u provide the solution wat the error?

Thanks 

tagMapping section in the pages section of the web.config

I found out that this patch would not fix my issue, which is to setfocus to the control that fails validation, and doubt if this is fixed in AJAX 2.0 as well.

In my case:

Validator Setting:

EnableClientScript="False"

SetFocusOnError="True"

Test Result 

Inside UpdatePanel fails

outside UpdatePanel works

So SetFocusOnError does something even when EnableClientScript is off when not being placed inside UpdatePanel. The behavior is not consistent.

Thank you for your respond,

 I tried it but I am still getting the error.  The thing is when I run the application to debug it on my machine every thing works fine.  The problem occurs only when I publish the website

 Hello,

 When I add this tag in my web.config, suddenly in all my .aspx.vb page every control who refers to an .aspx page or master page are not found anymore. ("control" is not a member of "....") Is there a property I need to set somewhere to avoid those error, atm I have no clue.

<system.web>
  <pages>
    <tagMapping>
       <add tagType="System.Web.UI.WebControls.RequiredFieldValidator" 
	     mappedTagType="System.Web.UI.Compatibility.RequiredFieldValidator,System.Web.Extensions, Version=1.0.61025.0, Culture=neutral,PublicKeyToken=31bf3856ad364e35"/>
    </tagMapping>
  </pages>
</system.web>

Unfortunately, despite of following instructions, the presence of the validators is blocking the updatepanel to work