OIF error Could not create pool connection. The DBMS driver exception was: IO Error: The Network Adapter could not establish the connection

 [ERROR] [FED-12064] [oracle.security.fed.model.util.rdbms.RDBMSConnectionManager] [tid: Thread-541] [userId: <anonymous>] [ecid: 0000Oe8_AWh8hoWzLwjO8A0000Hr000RcS,1:
20018] [APP: OIF#11.1.1.2.0] [URI: /fed/idp/initiatesso] Exception: {0}[[
weblogic.jdbc.extensions.ConnectionDeadSQLException: weblogic.common.resourcepool.ResourceDeadException: 0:weblogic.common.ResourceException: Could not create pool connection. The DBMS driver exception was: IO
 Error: The Network Adapter could not establish the connection
        at weblogic.jdbc.common.internal.JDBCUtil.wrapAndThrowResourceException(JDBCUtil.java:250)
        at weblogic.jdbc.common.internal.RmiDataSource.getPoolConnection(RmiDataSource.java:456)
        at weblogic.jdbc.common.internal.RmiDataSource.getConnectionInternal(RmiDataSource.java:538)
        at weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:498)
        at weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:491)
        at oracle.security.fed.model.util.rdbms.RDBMSConnectionManager.getConnection(RDBMSConnectionManager.java:210)
        at oracle.security.fed.jvt.discovery.model.artifact.RDBMSArtifactDiscoveryProvider.run(RDBMSArtifactDiscoveryProvider.java:256)
        at java.lang.Thread.run(Thread.java:722)

 [ERROR] [FED-12064] [oracle.security.fed.jvt.discovery.model.artifact.RDBMSArtifactDiscoveryProvider] [tid: Thread-541] [userId: <anonymous>] [ecid: 0000Oe8_AWh8hoWzL
wjO8A0000Hr000RcS,1:20018] [APP: OIF#11.1.1.2.0] [URI: /fed/idp/initiatesso] Exception: javax.naming.NamingException: Could not get an RDBMS Connection
[2016-09-09T22:10:24.362-05:00] [wls_oif1] [ERROR] [FED-11013] [oracle.security.fed.jvt.discovery.model.artifact.RDBMSArtifactDiscoveryProvider] [tid: Thread-541] [userId: <anonymous>] [ecid: 0000Oe8_AWh8hoWzL
wjO8A0000Hr000RcS,1:20018] [APP: OIF#11.1.1.2.0] [URI: /fed/idp/initiatesso] SQL error while interacting with the database.[[
java.sql.SQLException: Connection has already been closed.
        at weblogic.jdbc.wrapper.PoolConnection.checkConnection(PoolConnection.java:62)
        at weblogic.jdbc.wrapper.Connection.preInvocationHandler(Connection.java:100)
        at weblogic.jdbc.wrapper.PoolConnection_oracle_jdbc_driver_T4CConnection.rollback(Unknown Source)
        at oracle.security.fed.jvt.discovery.model.artifact.RDBMSArtifactDiscoveryProvider.run(RDBMSArtifactDiscoveryProvider.java:334)
        at java.lang.Thread.run(Thread.java:722)

Solution:

check OIF database setting. click on Edit and test connection for each data store setting.  it can be 2 reasons

1. database users password is expired
2. database is down.