This article is to resolve the error “Could not load file or assembly ‘System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35′ or one of its dependencies.”
If you ASP.NET solution is still based on .NET Framework 2.0 and you have the following line in Web.config.
<addassembly=“System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35“/>
In this case I might get the above mentioned error when you run your project.
What you need to do is download the Ajax installer fromhttp://www.microsoft.com/en-us/download/confirmation.aspx?id=883, install it, and run again.
Don’t waste your time to just copy the AjaxControlToolkit.dll into the bin folder without running the installation. It will be completely useless.