Web service can't be called from javascript after migrating from ASP.NET 2.0 to ASP.NET 3.5

Question

I have an ASP.NET 2.0 application (with Ajax Extensions 1.0) that I just migrated to ASP.NET 3.5.

In my app, I have a web service that's called from javascript (the service has the [ScriptService] attribute) and everything was working perfectly until I migrated my app. Now, the web service doesn't respond anymore.

Note: I don't use ScriptManager controls or any other fancy stuff. I generated the WebService proxy code using /mywebservice.asmx/js and the generated js file is added as a static js file in my app. I regenerated the JS file in 3.5 but it still doesn't work.

Any ideas?

Thanks in advance

Update:

Sorry for the missing information. I'm more of a backend dev and my javascript knowledge is generally poor. I'll try to trace the error in FireBug and post more information here (will have to figure out how to debug JS with FireBug first).

Update2

Sorry for wasting your time guys, I checked in Fiddler (which I should have done first before posting the question but somehow I assumed nothing was happening. I guess I'm just getting old and dumb!) and the webservice is actually working (I just checked the JSON response in Fiddler), so it seems to be a Javascript problem on the client.

@Chris, I can't post a comment on your answer (I get an error when I try to) so I'll just post it here. First, thanks a lot for your answer. Actually I use POST for the web service calls (the default setting in ASP.NET 2.0 and above)

Answer 1

How did you migrate the app? It sounds to me like you have a new web.config file which doesn't have http get enabled for web services

<configuration>
  <system.web>
    <webServices>
      <protocols>
        <add name="HttpGet"/>

Answer 2

Just to answer my own question: As I mentioned in the update, the problem was not that the web service wasn't working. The problem is actually that the JSON returned from the web service is different in 3.5. For the details, please see:

http://encosia.com/2009/02/10/a-breaking-change-between-versions-of-aspnet-ajax/