oracle.apps.fnd.common.PoolException: Exception creating new Poolable object.

Following error may appear when you click on AppsLocalLogin.jsp link while doing adconfig on DB tier:

JSP error
oracle.apps.fnd.common.PoolException: Exception creating new Poolable object.

It is best to have the services down while doing autoconfig, to avoid such errors.

I saw the same error when the database server had gone down and was not available due to hardware issues.  After the server came up and DB was started up, the error disappeared.