Pom.xml <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>4.3.6.Final</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>4.3.6.Final</version> </dependency> Error and Cause Determination Deploying a new WEBApplication using Hibernate fails with : Deploying /usr/local/wildfly-8.2.0.Final/standalone/deployments/WFJPA2PC-1.0.war "{\"JBAS014671: Failed services\" => {\"jboss.persistenceunit.\\\"WFJPA2PC-1.0.war#RacBankBHibPU\\\"\" => \"org.jboss.msc.service.StartException in service jboss.persistenceunit.\\\"WFJPA2PC-1.0.war#RacBankBHibPU\\\": org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set\"}}" Cause : Oracle RAC database was down ! Fix : Add hibernate.dialect to your persistence.xml <persistence-unit name="RacBankBHibPU" transaction-type="JTA"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>java:/jboss/datasources/xa_rac12g_bankb</jta-data-source> <class>com.hhu.wfjpa2pc.Accounts</class> <properties> <property name="hibernate.transaction.jta.platform" value="org.hibernate.service.jta.platform.internal.JBossAppServerJtaPlatform" /> <property name="hibernate.show_sql" value="true" /> <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/> </properties> </persistence-unit> -> Now application can be redeployed -> Application now starts but throws the following stack 08:55:04.761 javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/xa_rac12g_bankb 08:55:04.762 java.sql.SQLException: javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/xa_rac12g_bankb at org.jboss.jca.adapters.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:154) at com.hhu.wfjpa2pc.Jpa2pcTest.getRacInfoDS(Jpa2pcTest.java:398) at com.hhu.wfjpa2pc.Jpa2pcTest.getRacInfo(Jpa2pcTest.java:376) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl. -> With above Stack we easily can figure out that we need to start our RAC DB