“Internal Server Error” you connect to IBM WeBsphere Portal

Initial connection to the Portal Server via an HTTP server reports: "Internal Server Error".  Refreshing the browser results in a successful connection.

Enabling the plugin trace you can see the error

- TRACE: lib_rio: wait_on_socket: ServerIOTimeout fired.

In my case the IBM HTTP is on the same machine as Portal  and it's not a cluster.  The default value for ServerIOTimeout is -1.

Ajusting to ServerIOTimeout=120 solve the problem

You can see in the TN 1411685 that this problem was found on System I but my server is on Linux.