IIS 6.0\Event 1062 and Server Unavailable Errors
Within our IIS\OWA Front-End server configuration, we have 8 IIS virtuals that are defined for various types of applications. The Exchange apps, OWA, OMA, etc are still running ASP.Net 1.1, whereas a homebrew Mailbox reporting app requires ASP.Net 2.0. The applications were originally configured to run within the same IIS App Pool. Although it worked, we frequently began seeing errors with "Server Application Unavailable". The ultimate fix was an IISReset or boot of the server.
We later discovered from the Event logs, Event 1062 which states, "It is not possible to run two different versions of ASP.NET in the same IIS process. Please use the IIS Administration Tool to reconfigure your server to run the application in a separate process."
You cannot run more than one version of the framework in the same application pool in IIS6:
While multiple versions of the framework can co-exist on the same server, they can’t co-exist in the same process. This was not the case with IIS5.0. If you attempt to run multiple versions of the framework at the same time in the same process, the 2nd version that tries to run will fail with the following error:
"Server Application Unavailable "
What to do:
Fortunately, the solution is easy enough. Simply create a new application pool and move the site that you will be upgrading to that pool. You can even base it off of the configuration of the existing one if you don’t have the password memorized. During the new Application Pool creation, select the previous App Pool as a template and select create. One caveat is you may have to stop and start the IIS service. An IISRESET is performed after the change. Be sure to check the event logs for an additional errors.