I've just been going through the process of upgrading my development SharePoint sites to run on ASP.NET 2.0 and SQL server 2005.

First I installed the WSS Service Pack 2. No problems there.

Then I upgraded one of my sites to run on ASP.NET 2.0 using the nice new IIS property tab and running the stsadm -o upgrade -forceupgrade -url http://portalsiteurl command . The ststadm command updates the web.config in the IIS root directory and it also runs the contents of Web Server Extensions\60\TEMPLATE\SQL\STOREUP.SQL. This adds some new fields to tables and updates a lot of the core stored procedures.

An IISRESET later and I could browse to the WSS sites running on ASP.NET 2.0 with no problems.

The real problem came when I try to access another set of WSS sites that were running on a different IIS virtual server that gave me the dreaded Server Application Unavailable error

No panic as I knew from previous experience this is almost always a problem with Web.Config parsing or Application Pool configuration/identity .

Checking the Event Log gave me this

Fantastic, a helpful error message, it pointed me straight to the fact that the same Application Pool was in use by both Virtual Server applications and ASP.NET doesn't support loading a second version of .NET in the same worker process.

The fix is to create a new App Pool for the applications you want to run under ASP.NET 2.0. This would include any .Net applications that share an AppPool not just SharePoint.

Create a new App Pool based on the existing SharePoint one, give it a meaningful name

Assign it to the Virtual Server running SharePoint

an iisreset later and you should be good to go.

I'm so glad I don't try this stuff out on live servers, anymore.