# Exception on startup due to failing class enhancement with EnhancingClassTransformerImpl

**URL:** <https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640>\
**Category:** Hibernate ORM\
**Created:** [May 16, 2023, 7:25am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640 "2023-05-16T07:25:50Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![amir](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/amir/32/2415_2.png) [@amir](https://discourse.hibernate.org/u/amir)\
**Post date:** [May 16, 2023, 7:25am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640/1 "2023-05-16T07:25:50Z")

</div>

Trying to use hibernate 6.2.2 and run some tests that start spring application context. I’m using spring boot 3, which brings spring core libs version 6.0.0  
While it seems it doesn’t really affect anything I’m not sure what’s going on. The same test is fine with hibernate 6.1.7 and prior… We also use some code enhancements/instrumentation so we run tests/application with spring-instrument as java agent…  
Seems hibernate does some code enhancements, but I’m not sure why would it enhance spring classes ? I would expect enhancements should be done to entity classes and so on ? And it should filter out spring and other well-known packages ? But I didn’t find in the code any property that says accept packages/ignore packages…  
I believe it is failing because org/springframework/transaction/interceptor/TransactionAspectSupport$ReactiveTransactionSupport has some imports to Mono that I don’t have in the classpath for this test, but still want to understand can I ask hibernate to ignore some packages so it will not go through all the loaded classes and so speed up things on startup ? or enhancement is not really needed/expected in normal and it is only because I have spring-instrument as javaagent ?

```auto
jakarta.persistence.spi.TransformerException: Error performing enhancement of org/springframework/transaction/interceptor/TransactionAspectSupport$ReactiveTransactionSupport
	at org.hibernate.jpa.internal.enhance.EnhancingClassTransformerImpl.transform(EnhancingClassTransformerImpl.java:54)
	at org.springframework.orm.jpa.persistenceunit.ClassFileTransformerAdapter.transform(ClassFileTransformerAdapter.java:70)
	at org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver$FilteringClassFileTransformer.transform(InstrumentationLoadTimeWeaver.java:192)
	at java.instrument/java.lang.instrument.ClassFileTransformer.transform(ClassFileTransformer.java:244)
	at java.instrument/sun.instrument.TransformerManager.transform(TransformerManager.java:188)
	at java.instrument/sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:541)
	at java.base/java.lang.ClassLoader.defineClass1(Native Method)
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1012)
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:862)
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:760)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:681)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:639)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
	at java.base/java.lang.Class.getDeclaredMethods0(Native Method)
	at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3402)
	at java.base/java.lang.Class.getDeclaredMethods(Class.java:2504)
	at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:465)
	at org.springframework.util.ReflectionUtils.doWithLocalMethods(ReflectionUtils.java:320)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.checkLookupMethods(AutowiredAnnotationBeanPostProcessor.java:449)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.determineCandidateConstructors(AutowiredAnnotationBeanPostProcessor.java:341)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:1291)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1186)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:560)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:520)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205)
	at org.springframework.aop.support.AbstractBeanFactoryPointcutAdvisor.getAdvice(AbstractBeanFactoryPointcutAdvisor.java:116)
	at org.springframework.aop.aspectj.AspectJProxyUtils.isAspectJAdvice(AspectJProxyUtils.java:73)
	at org.springframework.aop.aspectj.AspectJProxyUtils.makeAdvisorChainAspectJCapableIfNecessary(AspectJProxyUtils.java:54)
	at org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator.extendAdvisors(AspectJAwareAdvisorAutoProxyCreator.java:95)
	at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findEligibleAdvisors(AbstractAdvisorAutoProxyCreator.java:98)
	at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.getAdvicesAndAdvisorsForBean(AbstractAdvisorAutoProxyCreator.java:78)
	at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:366)
	at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:318)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:434)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1773)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:598)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:520)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeanByName(AbstractAutowireCapableBeanFactory.java:457)
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:496)
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:467)
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:618)
	at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:242)
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:133)
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:300)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1416)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:597)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:520)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:973)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:916)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:584)
	at org.springframework.test.context.web.AbstractGenericWebContextLoader.loadContext(AbstractGenericWebContextLoader.java:228)
	at org.springframework.test.context.web.AbstractGenericWebContextLoader.loadContext(AbstractGenericWebContextLoader.java:105)
	at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.loadContext(AbstractDelegatingSmartContextLoader.java:212)
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:184)
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:118)
	at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:127)
	at org.springframework.test.context.web.ServletTestExecutionListener.setUpRequestContextIfNecessary(ServletTestExecutionListener.java:191)
	at org.springframework.test.context.web.ServletTestExecutionListener.prepareTestInstance(ServletTestExecutionListener.java:130)
	at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:241)
	at org.spockframework.spring.SpringTestContextManager.prepareTestInstance(SpringTestContextManager.java:56)
	at org.spockframework.spring.SpringInterceptor.interceptInitializerMethod(SpringInterceptor.java:46)
	at org.spockframework.runtime.extension.AbstractMethodInterceptor.intercept(AbstractMethodInterceptor.java:24)
	at org.spockframework.runtime.extension.MethodInvocation.proceed(MethodInvocation.java:101)
	at org.spockframework.runtime.PlatformSpecRunner.invoke(PlatformSpecRunner.java:398)
	at org.spockframework.runtime.PlatformSpecRunner.runInitializer(PlatformSpecRunner.java:259)
	at org.spockframework.runtime.PlatformSpecRunner.runInitializer(PlatformSpecRunner.java:254)
	at org.spockframework.runtime.IterationNode.prepare(IterationNode.java:31)
	at org.spockframework.runtime.SimpleFeatureNode.prepare(SimpleFeatureNode.java:32)
	at org.spockframework.runtime.SimpleFeatureNode.prepare(SimpleFeatureNode.java:15)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$2(NodeTestTask.java:123)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:123)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:90)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.spockframework.runtime.SpockNode.sneakyInvoke(SpockNode.java:40)
	at org.spockframework.runtime.SpecNode.lambda$around$0(SpecNode.java:63)
	at org.spockframework.runtime.PlatformSpecRunner.lambda$createMethodInfoForDoRunSpec$0(PlatformSpecRunner.java:61)
	at org.spockframework.runtime.model.MethodInfo.invoke(MethodInfo.java:156)
	at org.spockframework.runtime.PlatformSpecRunner.invokeRaw(PlatformSpecRunner.java:407)
	at org.spockframework.runtime.PlatformSpecRunner.invoke(PlatformSpecRunner.java:390)
	at org.spockframework.runtime.PlatformSpecRunner.runSpec(PlatformSpecRunner.java:55)
	at org.spockframework.runtime.SpecNode.around(SpecNode.java:63)
	at org.spockframework.runtime.SpecNode.around(SpecNode.java:11)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:147)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:127)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:90)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:55)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:102)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:57)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38)
	at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:232)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:55)

```

---

<div class="post-metadata">

**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [May 16, 2023, 9:09am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640/2 "2023-05-16T09:09:17Z")

</div>

Hibernate is just transforming and failing to do so for some reason, but it is Spring that invokes this transformation. So if you want to avoid transformation of certain classes, you’ll have to ask Spring folks about this.

---

<div class="post-metadata">

**Author:** ![amir](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/amir/32/2415_2.png) [@amir](https://discourse.hibernate.org/u/amir)\
**Post date:** [May 16, 2023, 10:07am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640/3 "2023-05-16T10:07:19Z")

</div>

Thanks, got it…  
found that hibernate is doing  
org.hibernate.jpa.boot.internal.PersistenceUnitInfoDescriptor#pushClassTransformer  
and depending on classpath availability, javaagent etc spring will register that class transformer and will invoke during classloading  
Seems the issue is that we have a javaagent and don’t have reactor lib in the classpath

---

<div class="post-metadata">

**Author:** ![amir](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/amir/32/2415_2.png) [@amir](https://discourse.hibernate.org/u/amir)\
**Post date:** [June 1, 2023, 9:53am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640/4 "2023-06-01T09:53:05Z")

</div>

just if someone will face similar issue  
org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl#EntityManagerFactoryBuilderImpl now does

```auto
			propertyValue = configurationValues.remove( AvailableSettings.ENHANCER_ENABLE_LAZY_INITIALIZATION );
			if ( propertyValue != null ) {
				lazyInitializationEnabled = Boolean.parseBoolean( propertyValue.toString() );
			}
			else {
				lazyInitializationEnabled = true;
			}

```

so it enables some bytecode enhancement by default if property is not set…  
and then does

```auto
if (dirtyTrackingEnabled || lazyInitializationEnabled || associationManagementEnabled) {
            EnhancementContext enhancementContext = this.getEnhancementContext(dirtyTrackingEnabled, lazyInitializationEnabled, associationManagementEnabled);
            persistenceUnit.pushClassTransformer(enhancementContext);

```

that’s why it might load and try to enhance something that is not really expected…  
it will also process imports and if there will be some import to something that you don’t use or even know it might fail.  
I think there should be filtration mechanism based on class name that will help to ignore some classes without really loading them by enhancer as loading can result in unexpected exceptions

---

<div class="post-metadata">

**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [June 1, 2023, 10:17am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640/5 "2023-06-01T10:17:51Z")

</div>

You can create an issue in the issue tracker([https://hibernate.atlassian.net](https://hibernate.atlassian.net)) for this. Maybe others agree with you that we should ignore transformation errors if they are caused by missing classes.

---

<div class="post-metadata">

**Author:** ![amir](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/amir/32/2415_2.png) [@amir](https://discourse.hibernate.org/u/amir)\
**Post date:** [June 1, 2023, 10:32am UTC](https://discourse.hibernate.org/t/exception-on-startup-due-to-failing-class-enhancement-with-enhancingclasstransformerimpl/7640/6 "2023-06-01T10:32:33Z")

</div>

[https://hibernate.atlassian.net/jira/software/c/projects/HHH/issues/HHH-16734](https://hibernate.atlassian.net/jira/software/c/projects/HHH/issues/HHH-16734)