I have just spent the last 2 days looking for why my Spring container (under Tomcat) was getting ClassNotFoundException and NoClassDefFoundError during start up. There is so much mis-leading stuff on the Internet. I had 2 projects in Eclipse: the core application project, that depends on, a different project containing all the hibernate and dao managers. Both projects’ JUnit tests work without any problems, but when I tried to launch the Tomcat container it failed with the following error:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ’sessionFactory’ defined in class path resource [uk/co/bigsoft/proj/database.xml]: Invocation of init method failed; nested exception is java.lang.NoClassDefFoundError: org/hibernate/usertype/UserType

I could confirm that the org.hibernate.usertype.UserType was in my Web Apps Libraries folder and was accessible by my application. I was on the verge of suicide when I found an article which provided a vital clue. The problem is caused by classloader dependencies - that is, the scope of jar files which are accessible by the application at a particular point. This point being during the Tomcat startup (bootstrapping phase). Although, I hit the problem with Hibernate it could happen with any User Entry jar. For completeness here was the full exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [uk/co/bigsoft/sm/config/database.xml]: Invocation of init method failed; nested exception is java.lang.NoClassDefFoundError: org/hibernate/usertype/UserType

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1362)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:540)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:485)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:455)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:251)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:169)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:248)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:170)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:407)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:735)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:369)
	at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:251)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:190)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4350)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
	at org.apache.catalina.core.StandardService.start(StandardService.java:516)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
	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.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Caused by: java.lang.NoClassDefFoundError: org/hibernate/usertype/UserType
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
	at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1275)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:169)
	at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:123)
	at org.hibernate.type.TypeFactory.heuristicType(TypeFactory.java:246)
	at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:283)
	at org.hibernate.cfg.Configuration$1.getIdentifierType(Configuration.java:2139)
	at org.hibernate.type.EntityType.getIdentifierType(EntityType.java:520)
	at org.hibernate.type.EntityType.getIdentifierOrUniqueKeyType(EntityType.java:545)
	at org.hibernate.type.ManyToOneType.getColumnSpan(ManyToOneType.java:88)
	at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:276)
	at org.hibernate.mapping.ToOne.isValid(ToOne.java:105)
	at org.hibernate.mapping.Property.isValid(Property.java:207)
	at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:458)
	at org.hibernate.mapping.RootClass.validate(RootClass.java:215)
	at org.hibernate.cfg.Configuration.validate(Configuration.java:1135)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1320)
	at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:753)
	at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:691)
	at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:211)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1390)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1359)
	... 29 more
Caused by: java.lang.ClassNotFoundException: org.hibernate.usertype.UserType
	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
	... 64 more
12-Nov-2008 12:04:56 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [uk/co/bigsoft/sm/config/database.xml]: Invocation of init method failed; nested exception is java.lang.NoClassDefFoundError: org/hibernate/usertype/UserType
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1362)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:540)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:485)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:455)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:251)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:169)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:248)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:170)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:407)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:735)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:369)
	at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:251)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:190)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4350)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
	at org.apache.catalina.core.StandardService.start(StandardService.java:516)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
	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.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Caused by: java.lang.NoClassDefFoundError: org/hibernate/usertype/UserType
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
	at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1275)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:169)
	at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:123)
	at org.hibernate.type.TypeFactory.heuristicType(TypeFactory.java:246)
	at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:283)
	at org.hibernate.cfg.Configuration$1.getIdentifierType(Configuration.java:2139)
	at org.hibernate.type.EntityType.getIdentifierType(EntityType.java:520)
	at org.hibernate.type.EntityType.getIdentifierOrUniqueKeyType(EntityType.java:545)
	at org.hibernate.type.ManyToOneType.getColumnSpan(ManyToOneType.java:88)
	at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:276)
	at org.hibernate.mapping.ToOne.isValid(ToOne.java:105)
	at org.hibernate.mapping.Property.isValid(Property.java:207)
	at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:458)
	at org.hibernate.mapping.RootClass.validate(RootClass.java:215)
	at org.hibernate.cfg.Configuration.validate(Configuration.java:1135)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1320)
	at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:753)
	at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:691)
	at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:211)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1390)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1359)
	... 29 more
Caused by: java.lang.ClassNotFoundException: org.hibernate.usertype.UserType
	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
	... 64 more