How to resolve the error "Servlet.service() for servlet dispatcher threw exception: org.hibernate.SessionException: Session is closed!"

If you try to get a connection from the entitymanager

                      ((SessionImpl)entityManager.getDelegate()).connection();

and still get an exception as below

Servlet.service() for servlet dispatcher threw exception: org.hibernate.SessionException: Session is closed!

then try to use like the below one to get the connection and dont forget to wrap up the method with @Transactional or open a transaction from a session.

@PersistenceContext
private EntityManager entityManager;

 Session session = entityManager.unwrap(Session.class);
 SessionImplementor sessionImplementor = (SessionImplementor) session;
 Connection cc = sessionImplementor.getJdbcConnectionAccess().obtainConnection();