>I've just tested replacing DLL's on a live site. As far as I can tell everything works as advertised. On the very first hit after the DLLs are replaced the Application_Start fires and the new version handles that and all subsquent hits. The old process completes any pending requests before it shuts down. This works when I am generating a stream of hits in quick succession whether or not the request handling takes some time but in the latter case, as above, the old process remains active until they are completed with the new process running in parallel.

I am trying to simulate that on a new project so I can submit that to you. So, I will try with a new project at first, with the same global.asax, the same .aspx pages and only one line in a DLL.

>I'm still not clear whether you have got your site to fail in circumstances other than when replacing DLLs (e.g under heavy load)?

It does it on recycle as well.

>But if you're not overriding any methods or handling any events in Global.asax it's hard to see how the way in which the process is launched and HttpApplication instances are created could be affected - i.e if you are just requesting a standard aspx page your framework doesn't enter into the picture.

Yes, but I have the feeling that when a new compile is in effect, even if the pages that I am clicking on does not use it, that the Web site is still trying to do something out of it.