Custom Application page Ajaxtoolkit error in Sharepoint 2010

Question

I recently migrated MOSS 2007 site to sharepoint 2010. The MOSS 2007 site included a custom application page. With IP address this page is working fine. I have deployed the dll in gac and placed the necessary forms in layouts folder. But using Internat or intranet dns I am getting below error:

 An error occurred during the compilation of the requested file, or one of its dependencies. The type 'AjaxControlToolkit.SliderExtender' exists in both 'c:\Windows\assembly\GAC_MSIL\AjaxControlToolkit\3.0.30930.28736__28f01b0e84b6d53e\AjaxControlToolkit.dll' and 'c:\Windows\Microsoft.NET\Framework64\v2.0.50727\Temporary ASP.NET Files\root\e2b85a3a\aefa6379\assembly\dl3\6cf6a9f3\d0ee2c06_53facd01\AjaxControlToolkit.DLL' 

If I delete the dll placed in Temporary ASp.net folder it says not able to find the dll in the temporary folder url. N if i delete gac dll it looks for the dll in gac n throws the same error of unable to find. I have provided below ajax entry in web.config but its still showing me the same error.

  <add namespace="AjaxControlToolkit" assembly="AjaxControlToolkit, Version=3.0.30930.28736, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e" tagPrefix="ajaxToolkit"/>
      </controls>

and in tag i added the assembly entry

Answer 1

Try replacing your Ajax Control Toolkit which is compatible with .Net Framework 3.5.

As you have migrated from MOSS 2007, your existing Ajax Control Toolkit might be compatible with .Net Framework 2.0 only.