AjaxControlToolkit reference in VS2010 with .NET 2.0

Question

I have a strange problem when attempting to compile an old website which is hamstrung with .NET 2.0 and VS2010.

I've installed ASP.NET AJAX 1.0 and I have the AjaxControlToolkit binary referenced in the project, both resolve just fine and appear in the Object Browser. Code highlighter also shows their presence is detected.

However, when I try to compile, AjaxControlToolkit disappears from the Object Browser and I get a whole bunch of "'AjaxControlToolkit' is not declared" errors. I have to reload the solution in VS for it to reappear in the Object Browser.

The AjaxControlToolkit reference has the following attributes:

Description: Ajax Control Toolkit
Identity: AjaxControlToolkit
Resolved: True
Runtime Version: v2.0.50727
Specific Version: False
Strong Name: True
Version: 1.0.11119.25055

Any ideas?

Answer 1

I can't believe I missed this (well, okay, the message only showed up after trying to recompile a zillion times and deleting/changing files), but there was a warning about being unable to resolve a reference to System.Web.Extensions.Design -- the project didn't have a reference to this despite having a reference to System.Web.Extensions and being compileable before.

After re-adding the reference, the website compiles. They should really promote that warning to an error!