ASP.NET: WebResource.axd call 404 error: how to know which assembly/resource is missing or responsible?

Question

I get a 404 HTTP status error (not found) on a specific WebResource.axd call inside an ASP.NET 3.5 (AJAX) web application. I guess the erro

Answer 1

Is your project missing any references?

Are there any references set to CopyLocal=False (common with Infragistics or GAC'ed refs) that dont make it to the destination?

A utility like reflector or dependency walker will tell you if your main assembly is missing any dependencies that are not immediately obvious.

Does the Application_Error handler in global.asax have a catch that is producing any error info (FileNotFoundExceptions)?

Did you set custom errors to 'remote only' and browse the site from the local machine?