I need to research this a bit more, but I will give a quick fix that I did.
So, I started an AJAX Web Application in Visual Studio 2008 and then added the latest Ajax Control Toolkit for 3.5. I made a simple page and wanted to use the Auto Complete Control. So, I added a simple text box and then added the Auto Complete Extender. There was then a item to add the event of this control to your code behind.
I got this error:
Cannot create page method “GetCompletionList” because no CodeBehind or CodeFile was found.
I spent quite a few hours looking throuh solutions and couldn’t find anything that was of much help.
I decided to start over. I created the application a little differently this time. Instead of a new project, I started a New Web Site. Repeated the same steps and it works fine.
The problem has to do with VSWebProjectItem. The standard AJAX Web Application with project file does not consider itself a “Web Project” and causes the AJAX toolkit to error.