ASP.NET 4 UpdatePanel and IIS7 Problem

I have an ASP.NET 4 webpage that contains an update panel which just allows me to add a few items to a drop down list without reloading the entire 开发者_运维知识库page.

The page works fine on the Visual Studio 2010 ASP.NET Development Server, performs the Async call and the page is properly laid out. However, when I deploy the page to IIS7, the Async call no longer works (the page is completely reloaded) and the layout of some items on the page is incorrect.

I used Fiddler to look at what's happening and it looks like there are 404's when the page tries to access ScriptResource.axd, with everything else working correctly. I think that has to do with the Javascript required for the call but I'm not sure how to fix it. Any suggestions?

I had the same issue. After reading, this and this2 I checked the ISAPI handlers definition in the root site of my IIS, but it looked fine, so I kept struggling some more.

Finally fixed it by realizing the ISAPI Handlers definition had been modified at the site level, and wasnt inheriting the same definitions as in the root site. It was fixed selecting my site in IIS Manager, going to the "Handler Mappings" section, and then clicking in "Revert To Inherited".