Chris Stepnitz [http://community.jboss.org/people/cstepnitz] created the discussion "JBoss 5.0 and 5.1 MySql-Hibernate Dialect Class Cast error--works in JBoss 4.2.3" To view the discussion, visit: http://community.jboss.org/message/548056#548056 -------------------------------------------------------------- Hi, I'm trying to migrate my application to JBoss 5.1 or  JBoss 5.0.1 from JBoss 4.2.3, and I'm having some issues with the hibernate-to-mysql database  connection.  Both new versions of JBoss give me the same  error, while the same configuration works in JBoss 4.2.3. In short, I've successfully set up a data source  connection and jndi name for my war to a local mysql database.  My app itself uses hibernate to  'talk' to the database, and on deployment I get a ClassCast exception stating that  the default MySql dialect doesn't extend the right class (but it does!).   "Caused by: java.lang.ClassCastException:  org.hibernate.dialect.MySQLDialect  cannot be cast to  org.hibernate.dialect.Dialect" I'm mystified.  Any guesses?  Details  below. *Stack Trace:* 08:32:31,453 INFO  [Version] Hibernate Commons  Annotations 3.1.0.GA 08:32:31,453 INFO  [Version] Hibernate EntityManager  3.4.0.GA 08:32:31,500 INFO  [Ejb3Configuration] Processing  PersistenceUnitInfo [         name: MyPersistence          ...] 08:32:31,546 WARN  [Ejb3Configuration] Persistence provider caller does  not impl ement the EJB3 spec correctly.  PersistenceUnitInfo.getNewTempClassLoader() is null. 08:32:31,625 INFO   [HibernateSearchEventListenerRegister] Unable to find  org.hibernate.search.event.FullTextIndexEventListener on the classpath.  Hibernate Search is not enabled. 08:32:31,640 INFO   [InjectedDataSourceConnectionProvider] Using provided datasource 08:32:32,093  ERROR [AbstractKernelController] Error installing to Start:  name=persistence.unit:unitName=#MyPersistence  state=Create javax.persistence.PersistenceException: [PersistenceUnit:  MyPersistence] Unable to build EntityManagerFactory         at  org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677)          at  org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:132)          at  org.jboss.jpa.deployment.PersistenceUnitDeployment.start(PersistenceUnitDeployment.java:301)          at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)         at  sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)          at  sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)          at java.lang.reflect.Method.invoke(Method.java:597)         at  org.jboss.reflect.plugins.introspection.ReflectionUtils.invoke(ReflectionUtils.java:59)          at  org.jboss.reflect.plugins.introspection.ReflectMethodInfoImpl.invoke(ReflectMethodInfoImpl.java:150)          at  org.jboss.joinpoint.plugins.BasicMethodJoinPoint.dispatch(BasicMethodJoinPoint.java:66)          at  org.jboss.kernel.plugins.dependency.KernelControllerContextAction$JoinpointDispatchWrapper.execute(KernelControllerContextAction.java:241)          at  org.jboss.kernel.plugins.dependency.ExecutionWrapper.execute(ExecutionWrapper.java:47)          at  org.jboss.kernel.plugins.dependency.KernelControllerContextAction.dispatchExecutionWrapper(KernelControllerContextAction.java:109)          at  org.jboss.kernel.plugins.dependency.KernelControllerContextAction.dispatchJoinPoint(KernelControllerContextAction.java:70)          at  org.jboss.kernel.plugins.dependency.LifecycleAction.installActionInternal(LifecycleAction.java:221)          at  org.jboss.kernel.plugins.dependency.InstallsAwareAction.installAction(InstallsAwareAction.java:54)          at  org.jboss.kernel.plugins.dependency.InstallsAwareAction.installAction(InstallsAwareAction.java:42)          at  org.jboss.dependency.plugins.action.SimpleControllerContextAction.simpleInstallAction(SimpleControllerContextAction.java:62)          at  org.jboss.dependency.plugins.action.AccessControllerContextAction.install(AccessControllerContextAction.java:71)          at  org.jboss.dependency.plugins.AbstractControllerContextActions.install(AbstractControllerContextActions.java:51)          at  org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)          at  org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631)          at  org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934)          [CUT HERE FOR LENGTH] Caused by: org.hibernate.HibernateException: Could  not instantiate dialect class         at  org.hibernate.dialect.DialectFactory.buildDialect(DialectFactory.java:84)          at  org.hibernate.dialect.DialectFactory.determineDialect(DialectFactory.java:66)          at  org.hibernate.dialect.DialectFactory.buildDialect(DialectFactory.java:39)          at  org.hibernate.cfg.SettingsFactory.determineDialect(SettingsFactory.java:426)          at  org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:128)          at  org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2073)          at  org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1298)          at  org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867)          at  org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669)          ... 61 more Caused by: java.lang.ClassCastException:  org.hibernate.dialect.MySQLDialect cannot be cast to  org.hibernate.dialect.Dialect         at  org.hibernate.dialect.DialectFactory.buildDialect(DialectFactory.java:78)          ... 69 more         08:32:34,234 INFO  [TomcatDeployment] deploy,  ctxPath=/myCtx 08:33:03,250 INFO  [[/myCtx]] Initializing log4j from  [classpath:log4j.xml] 08:33:03,281 INFO  [[/myCtx]] Initializing Spring root  WebApplicationContext *My Data Source:* <?xml version="1.0"  encoding="UTF-8"?> <datasources>    <local-tx-datasource>        <jndi-name>MyPersistence</jndi-name>        <jta-data-source>MyPersistence</jta-data-source>        <connection-url>jdbc:mysql://localhost:3306/myApp</connection-url>        <driver-class>com.mysql.jdbc.Driver</driver-class>        <user-name>FAKEUSER</user-name>        <password>FAKEPASSWORD</password>        <min-pool-size>5</min-pool-size>        <max-pool-size>20</max-pool-size>        <idle-timeout-minutes>0</idle-timeout-minutes>       <track-statements/>       <application-managed-security/>         <prepared-statement-cache-size>32</prepared-statement-cache-size>     </local-tx-datasource> </datasources> *My Persistence.xml in my.war* <persistence xmlns=" /java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence"  version="1.0">      <persistence-unit  transaction-type="JTA">           <jta-data-source>java:/MyPersistence</jta-data-source>        </persistence-unit> </persistence> -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/548056#548056] Start a new discussion in Datasource Configuration at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&...]