Where to get and how to install (or migrate) missing assemblies for ASP.NET server?

Question

I am migrating web apps to new hosting servers, but when I try to access them to test on the new server, I get all these assemblies not found errors like:

Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Could not load file or assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

Source Error:

Line 28:     <compilation debug="false">
Line 29:      <assemblies>
Line 30:       <add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
Line 31:       <add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
Line 32:       <add assembly="System.Web.Extensions.Design, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>

Does anyone know where you find these to install or how to migrate them over?

Answer 1

That's part of the ASP.Net AJAX kit.

Answer 2

http://www.asp.net/ajax/downloads/

Answer 3

Moved from Joel's post comments....

You will have to either install the ASP.AJAX kit on the server, or include the assemblies in your project. Here, and here will say you how you can include the libraries as DLL or as JS.