AjaxControlToolkit Version Problem

If you have more than one version of AJAX Tool Kit in your System , there might be problem while  developing an AJAX based pages ,

Error Message

 Error 2 Assembly 'AjaxControlToolkit, Version=3.0.30512.17815, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' uses 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' which has a higher version than referenced assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

Solution  

This is due to the version Conflict , to solve this add the following tag in your web config file  

<runtime>

<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">

<dependentAssembly>

<assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35" Culture="neutral"/>

<bindingRedirect oldVersion="1.0.61025.0" newVersion="3.5.0.0"/>

<publisherProfile apply="no"/>

</dependentAssembly>

</assemblyBinding>

</runtime>