Handlers returns 404 error on IIS7.5 integrated pipeline

Answer 1

I recently moved a client website from an old IIS6 to IIS7 installation. They were running into 404s on their application when calling .axd also. Their site was set to .net 2, permissions correct, handlers all looked good. Ended up changing their application pool from "Managed Pipeline Mode" Integrated to Classic, this solved the problem for their application.