This paper discusses techniques for diagnosing problems that are related to the Web server plug-in for WebSphere Application Server V6, including those resulting from configuration errors. The Web server plug-ins handle communications between a Web server and the Web container in an application server or servers. Symptoms of a problem that involve the plug-in include:

- Users cannot access an application through the Web server

- Load balancing and failover are not working properly

- Session data is being lost

- Slow or intermittent application response

- The Web server will not start after plug-in installation or configuration

The Web server plug-in works with six different Web servers. However, this paper concentrates on the IBM HTTP Server and its plug-in. It does not address Web server problems or problems that are related to the application server Web container.

This paper applies to WebSphere Application Server V6 for distributed systems only. It does not cover WebSphere Application Server for z/OS.