Did that link I gave with the list of reasons it could occur not help?
The product provides a special subclass of java.sql.SQLException when using connection pooling to access a relational database. This com.ibm.websphere.ce.cm.StaleConnectionException subclass exists in both a WebSphere 4.0 data source and in the new data source using the relational resource adapter, and is used to indicate that the connection currently held is no longer valid. This situation can occur for many reasons, including the following:
* The application tries to get a connection and fails, as when the database is not started.
* A connection is no longer usable because of a database failure. When an application tries to use a previously obtained connection, the connection is no longer valid. In this case, all connections currently in use by the application can get this error when they try to use the connection.
* The connection is orphaned (because the application had not used it in at most two times the value of the unused timeout setting) and the application tries to use the orphaned connection. This case applies only to Version 4.0 data sources.
* The application tries to use a
JDBC resource, such as a statement, obtained on a stale connection.
* A connection is closed by the Version 4.0 data source auto connection cleanup and is no longer usable. Auto connection cleanup is the standard mode in which connection management operates. This mode indicates that at the end of a transaction, the transaction manager closes all connections enlisted in that transaction. This enables the transaction manager to ensure that connections are not held for excessive periods of time and that the pool does not reach its maximum number of connections prematurely.
One ramification of having the transaction manager close the connections and return the connection to the free pool after a transaction ends, is that an application cannot obtain a connection in one transaction and try to use it in another transaction. If the application tries this, a StaleConnectionException is thrown because the connection is already closed.