What is the purpose of the Assemblies node in Web.Config?

Question

When creating a new ASP.NET AJAX Web Application in Visual Studio 2005, the default web.config contains the following section (inside the compilation node):

<assemblies>
    <add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
</assemblies>

Whether or not the assemblies node exists doesn't seem to affect the AJAX functionality. Update panels, etc work fine regardless of whether or not the reference to System.Web.Extensions is included in Web.Config.

What's the purpose of this section, and can it be safely removed?

Answer 1

It may or may not be safely removed. The Assemblies node is for configuration-based reference addition. It's used by ASP.NET websites that deploy uncompiled .cs code files to their website, rather than (as sensible people do) compiled assemblies.

If you are deploying code-behind files to your website rather than assemblies, then keep it in. If you are deploying assemblies, remove it.

Answer 2

Rick Strahl's Web log has short but concisely explaining article on the subject.