Yoann Rodière ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiOGU2MWQxZDY1... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-15606?atlOrigin=eyJpIjoiOGU2MW... ) HHH-15606 ( https://hibernate.atlassian.net/browse/HHH-15606?atlOrigin=eyJpIjoiOGU2MW... ) @OneToOne(mappedBy = ..., fetch = LAZY) in embedded leads to IllegalArgumentException: Can not set [...] to LazyPropertyInitializer$1 ( https://hibernate.atlassian.net/browse/HHH-15606?atlOrigin=eyJpIjoiOGU2MW... ) Change By: Yoann Rodière ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) Affects Hibernate ORM 6.2, probably also 6.1 and 6.0, but definitely not 5.6. This With bytecode enhancement enabled, this model: {noformat} @Entity(name = "entitya") public static class EntityA { @Id private Integer id; @Embedded private EmbeddedValue embedded = new EmbeddedValue(); public EntityA() { } private EntityA(Integer id) { this.id = id; } public Integer getId() { return id; } public EmbeddedValue getEmbedded() { return embedded; } public void setEmbedded(EmbeddedValue embedded) { this.embedded = embedded; } } @Embeddable public static class EmbeddedValue implements Serializable { @OneToOne(mappedBy = "entityA", fetch = FetchType.LAZY) private EntityB entityB; public EmbeddedValue() { } public EntityB getEntityB() { return entityB; } public void setEntityB( EntityB entityB) { this.entityB = entityB; } } @Entity(name = "entityb") public static class EntityB { @Id private Integer id; @OneToOne private EntityA entityA; public EntityB() { } private EntityB(Integer id) { this.id = id; } public Integer getId() { return id; } public EntityA getEntityA() { return entityA; } public void setEntityA(EntityA entityA) { this.entityA = entityA; } }{noformat} Leads to this stacktrace upon loading EntityA: {noformat}org.hibernate.InstantiationException: Could not instantiate entity:  : org.hibernate.orm.test.bytecode.enhancement.lazy.proxy.LazyOneToOneMappedByInEmbeddedTest$EmbeddedValue at org.hibernate.metamodel.internal.EmbeddableInstantiatorPojoStandard.instantiate(EmbeddableInstantiatorPojoStandard.java:84) at org.hibernate.sql.results.graph.embeddable.AbstractEmbeddableInitializer.createCompositeInstance(AbstractEmbeddableInitializer.java:326) at org.hibernate.sql.results.graph.embeddable.AbstractEmbeddableInitializer.prepareCompositeInstance(AbstractEmbeddableInitializer.java:242) at org.hibernate.sql.results.graph.embeddable.AbstractEmbeddableInitializer.initializeInstance(AbstractEmbeddableInitializer.java:190) at org.hibernate.sql.results.internal.StandardRowReader.coordinateInitializers(StandardRowReader.java:153) at org.hibernate.sql.results.internal.StandardRowReader.readRow(StandardRowReader.java:98) at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:184) at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:33) at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.doExecuteQuery(JdbcSelectExecutorStandardImpl.java:443) at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.executeQuery(JdbcSelectExecutorStandardImpl.java:166) at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.list(JdbcSelectExecutorStandardImpl.java:91) at org.hibernate.sql.exec.spi.JdbcSelectExecutor.list(JdbcSelectExecutor.java:31) at org.hibernate.loader.ast.internal.SingleIdLoadPlan.load(SingleIdLoadPlan.java:140) at org.hibernate.loader.ast.internal.SingleIdLoadPlan.load(SingleIdLoadPlan.java:110) at org.hibernate.loader.ast.internal.SingleIdEntityLoaderStandardImpl.load(SingleIdEntityLoaderStandardImpl.java:72) at org.hibernate.persister.entity.AbstractEntityPersister.doLoad(AbstractEntityPersister.java:4338) at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4328) at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:589) at org.hibernate.event.internal.DefaultLoadEventListener.loadFromCacheOrDatasource(DefaultLoadEventListener.java:575) at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:544) at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:537) at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:199) at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:238) at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:103) at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:75) at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:118) at org.hibernate.internal.SessionImpl.fireLoadNoChecks(SessionImpl.java:1241) at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1229) at org.hibernate.loader.access.IdentifierLoadAccessImpl.doLoad(IdentifierLoadAccessImpl.java:192) at org.hibernate.loader.access.IdentifierLoadAccessImpl.lambda$load$1(IdentifierLoadAccessImpl.java:158) at org.hibernate.loader.access.IdentifierLoadAccessImpl.perform(IdentifierLoadAccessImpl.java:105) at org.hibernate.loader.access.IdentifierLoadAccessImpl.load(IdentifierLoadAccessImpl.java:158) at org.hibernate.internal.SessionImpl.get(SessionImpl.java:1021) at org.hibernate.orm.test.bytecode.enhancement.lazy.proxy.LazyOneToOneMappedByInEmbeddedTest.lambda$test$1(LazyOneToOneMappedByInEmbeddedTest.java:51) at org.hibernate.testing.transaction.TransactionUtil2.inTransaction(TransactionUtil2.java:96) at org.hibernate.testing.transaction.TransactionUtil2.lambda$inTransaction$0(TransactionUtil2.java:76) at org.hibernate.testing.transaction.TransactionUtil2.inSession(TransactionUtil2.java:35) at org.hibernate.testing.transaction.TransactionUtil2.inTransaction(TransactionUtil2.java:74) at org.hibernate.testing.junit4.BaseNonConfigCoreFunctionalTestCase.inTransaction(BaseNonConfigCoreFunctionalTestCase.java:591) at org.hibernate.orm.test.bytecode.enhancement.lazy.proxy.LazyOneToOneMappedByInEmbeddedTest.test(LazyOneToOneMappedByInEmbeddedTest.java:50) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56) at org.hibernate.testing.junit4.ExtendedFrameworkMethod.invokeExplosively(ExtendedFrameworkMethod.java:45) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27) at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:299) at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:293) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.lang.Thread.run(Thread.java:829) Caused by: org.hibernate.PropertyAccessException: Could not set value of type [org.hibernate.bytecode.enhance.spi.LazyPropertyInitializer$1] : `org.hibernate.orm.test.bytecode.enhancement.lazy.proxy.LazyOneToOneMappedByInEmbeddedTest$EmbeddedValue.entityB` (setter) at org.hibernate.property.access.spi.SetterFieldImpl.set(SetterFieldImpl.java:79) at org.hibernate.property.access.spi.EnhancedSetterImpl.set(EnhancedSetterImpl.java:38) at org.hibernate.metamodel.mapping.internal.AbstractEmbeddableMapping.lambda$setValues$1(AbstractEmbeddableMapping.java:106) at org.hibernate.metamodel.mapping.internal.EmbeddableMappingTypeImpl.forEachAttributeMapping(EmbeddableMappingTypeImpl.java:720) at org.hibernate.metamodel.mapping.internal.AbstractEmbeddableMapping.setValues(AbstractEmbeddableMapping.java:105) at org.hibernate.metamodel.internal.EmbeddableInstantiatorPojoStandard.instantiate(EmbeddableInstantiatorPojoStandard.java:78) ... 54 more Caused by: java.lang.IllegalArgumentException: Can not set org.hibernate.orm.test.bytecode.enhancement.lazy.proxy.LazyOneToOneMappedByInEmbeddedTest$EntityB field org.hibernate.orm.test.bytecode.enhancement.lazy.proxy.LazyOneToOneMappedByInEmbeddedTest$EmbeddedValue.entityB to org.hibernate.bytecode.enhance.spi.LazyPropertyInitializer$1 at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167) at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171) at java.base/jdk.internal.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81) at java.base/java.lang.reflect.Field.set(Field.java:780) at org.hibernate.property.access.spi.SetterFieldImpl.set(SetterFieldImpl.java:52) ... 59 more{noformat} ( https://hibernate.atlassian.net/browse/HHH-15606#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-15606#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100209- sha1:13f5f09 )