ASP.NET – Fixing WebResource.axd and ScriptResource.axd 404 Not Found

Open the full URLs of the source files (...ScriptResource.axd...) in a new browser window. You should see some JavaScript content. If not, the asp.net ajax components are not correctly installed.

Sys is not defined

indicates that the Ajax client side component is not there, the sys class can not be found.

If you are using .net 3.5 it is part of the framework and they problem should be in web.config, when using .net 2.0 you need ASP.NET AJAX 1.0, if you install this msi on the server, the files go into the GAC, the central place for .net components. You could put the single file System.Web.Extensions.dll into your bin directory without installing the msi, but you still need the correct settings in the web.config file. The site ajax.asp.net has lots of information about all this.

Well after obtaining access to our client's site (through WebSEAL) and building a test case, we have an answer. According to IBM's documentation on AJAX and WebSEAL, at the very end on the section of Junction cookies there's a paragraph that reads:

Potential solution.

If the response from an AJAX request is not to be rendered as HTML, the response should not be sent with a content type of "text/html". A more appropriate content type should be used, for example, "text/plain". WebSEAL does not add the junction cookie code to responses that do not have a content type of "text/html"

For our ASP.NET application, it was a simple condition to add into the Page_Load event that used the control.

   protected void Page_Load(object sender, EventArgs e)
   {

     Response.Clear();

     Response.ContentType = (Page.IsCallback) ? "text/plain" : "text/html";

     //does same thing as line above
     //if (Page.IsCallback)
     //   Response.ContentType = "text/plain";
     //else
     //   Response.ContentType = "text/html";

   }

I'm sure that other languages (PHP,JSP,RoR,etc.) all have ways of altering content type. In terms of ASP.NET, I'm not sure if there's a better lifecycle event method to put this in (PreInit?), but this is an effective workaround for this specific issue with AJAX and IBM WebSEAL reverse proxy junction cookies.