DefaultAppPool and Classic .NET pool on IIS7

Question

I have moved a web application with Atlas implementation from IIS6 to IIS7. There are sections in this application that have Ajax implementation. Due to constraints the Atlas was not converted to Ajax.

The parts were Ajax is implemented, the application works fine, but client side events fired using Atlas throw an 'UnKnown error'.

I change the Application Pool of the site to Classic .NET AppPool and it works fine.

I could not find the reason why Atlas does not work on IIS7 DefaultAppPool and what changes when the Application Pool is changed to Classic. Has someone faced this problem and does anyone have insights into this?

Answer 1

See this question which gives some information on the differences. The referenced document at http://learn.iis.net/page.aspx/101/introduction-to-iis-7-architecture/ is useful.