See http://opensource.atlassian.com/projects/hibernate/browse/HHH-2222 It was answered in the post http://forum.springframework.org/showthread.php?t=18124 However the solution provided doesnt work for me, also I dont see how it would work, the version in the dependencies in the hibernate pom and in the spring pom are different. Its not a problem due to including a jar by mistake. I tried to solve the problem by trying to force hibernate to use the spring version of the asm jar: Here are the steps I tried in the pom <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate</artifactId> <version>3.2.5.ga</version> <exclusions> <exclusion> <groupId>asm</groupId> <artifactId>asm</artifactId> </exclusion> <exclusion> <groupId>asm</groupId> <artifactId>asm-attrs</artifactId> </exclusion> </exclusions> </dependency> <!-- Dependency added to fix: Caused by: java.lang.NoClassDefFoundError: org/objectweb/asm/commons/EmptyVisitor at java.lang.ClassLoader.defineClass1(Native Method) ... at org.springframework.core.type.filter.AnnotationTypeFilter.matchSelf(AnnotationTypeFilter.java:52) at org.springframework.core.type.filter.AbstractTypeHierarchyTraversingFilter.match(AbstractTypeHierarchyTraversingFilter.java: 54) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.isCandidateComponent(ClassPathScanningCan didateComponentProvider.java:183) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.getClassReaderIfCandidate(ClassPathScanni ngCandidateComponentProvider.java:166) ... --> <dependency> <groupId>asm</groupId> <artifactId>asm-commons</artifactId> <version>2.2.3</version> </dependency> <!-- Fix error: asm version 2.0 + Caused by: java.lang.NoClassDefFoundError: org/objectweb/asm/FieldVisitor ... at org.springframework.core.type.filter.AnnotationTypeFilter.matchSelf(AnnotationTypeFilter.java:52) at org.springframework.core.type.filter.AbstractTypeHierarchyTraversingFilter.match(AbstractTypeHierarchyTraversingFilter.java: 54) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.isCandidateComponent(ClassPathScanningCan didateComponentProvider.java:183) --> <!-- Fixing this gives Caused by: java.lang.NoClassDefFoundError: org/objectweb/asm/CodeVisitor at net.sf.cglib.core.KeyFactory$Generator.generateClass(KeyFactory.java:165) at net.sf.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25) at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:216) at net.sf.cglib.core.KeyFactory$Generator.create(KeyFactory.java:145) at net.sf.cglib.core.KeyFactory.create(KeyFactory.java:117) at net.sf.cglib.core.KeyFactory.create(KeyFactory.java:108) at net.sf.cglib.core.KeyFactory.create(KeyFactory.java:104) at net.sf.cglib.proxy.Enhancer.<clinit>(Enhancer.java:69) at org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.getProxyFactory(CGLIBLazyInitializer.java:117) at org.hibernate.proxy.pojo.cglib.CGLIBProxyFactory.postInstantiate(CGLIBProxyFactory.java:43) at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:162) Code Visitor is in asm 1.5.3 or before Then an exception that a method doesnt exist ... There are several web pages that document the fact (including a patch to hibernate (which isnt implemented) http://blog.interface21.com/main/2007/06/11/asm-version-incompatibilities-using-spring-autowired-with-hibernate/ http://blog.interface21.com/main/2007/06/11/asm-version-incompatibilities-using-spring-autowired-with-hibernate/feed/ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2222 http://forum.springframework.org/showthread.php?p=127012#poststop The solution seems to be: create a fork of the asm project, changing the package name, and recompile the spring source with that version. The asm developers really should do that anyway if they break the compatibility at each change in the VM. I know its not the ideal solution, but I cant think of a better one. Or could you explain how to run hibernate on a different class loader to spring inside tomcat? i tried to get hibernate to use javassist but that didnt cure the problem. I would have used OSGi but there doesnt seem to be a hibernate implementation just yet. Hope you can provide a fix soon, its a major showstopper for me.