Unexpected exception while enlisting XAConnection:

Caused by: java.sql.SQLException: Unexpected exception while enlisting XAConnection 
java.sql.SQLException: Transaction rolled back: Transaction timed out after 50 seconds
BEA1-450F175C33A65FA1D8A0
at weblogic.jdbc.jta.DataSource.enlist(DataSource.java:1431)
at weblogic.jdbc.jta.DataSource.refreshXAConnAndEnlist(DataSource.java:1331)
at weblogic.jdbc.jta.DataSource.getConnection(DataSource.java:426)
at weblogic.jdbc.jta.DataSource.connect(DataSource.java:383)
at weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSource.java:346)
at oracle.toplink.jndi.JNDIConnector.connect(JNDIConnector.java:123)
at oracle.toplink.jndi.JNDIConnector.connect(JNDIConnector.java:84)
at oracle.toplink.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:153)
at oracle.toplink.internal.databaseaccess.DatasourceAccessor.connectInternal(DatasourceAccessor.java:273)
at oracle.toplink.internal.databaseaccess.DatabaseAccessor.connectInternal(DatabaseAccessor.java:230)
at oracle.toplink.internal.databaseaccess.DatasourceAccessor.reconnect(DatasourceAccessor.java:478)
at oracle.toplink.internal.databaseaccess.DatabaseAccessor.reconnect(DatabaseAccessor.java:1342)
at oracle.toplink.internal.databaseaccess.DatasourceAccessor.incrementCallCount(DatasourceAccessor.java:251)
at oracle.toplink.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:511)
at oracle.toplink.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:467)
at oracle.toplink.internal.sessions.AbstractSession.executeCall(AbstractSession.java:800)
at oracle.toplink.internal.sessions.IsolatedClientSession.executeCall(IsolatedClientSession.java:115)
at oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeCall(
DatasourceCallQueryMechanism.java:193)
at oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeCall(
DatasourceCallQueryMechanism.java:179)
at oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeNoSelectCall(
DatasourceCallQueryMechanism.java:222)
at oracle.toplink.internal.queryframework.DatasourceCallQueryMechanism.executeNoSelect(
DatasourceCallQueryMechanism.java:202)
at oracle.toplink.queryframework.DataModifyQuery.executeDatabaseQuery(DataModifyQuery.java:55)
at oracle.toplink.queryframework.DatabaseQuery.execute(DatabaseQuery.java:674)
at oracle.toplink.queryframework.DatabaseQuery.executeInUnitOfWork(DatabaseQuery.java:597)
at oracle.toplink.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2741)

This exception thrown out due to the JTA time out specified in application server exceeded for the connection. Here in this exception, 50seconds specified and crossed the limit. We can increase this number(upto 600s) and test the application , if still problem persist, then we have to eye on Database.

Read More about ConnectionDeadSQLException