IT Support ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *commented* on HHH-9662 ( https://hibernate.atlassian.net/browse/HHH-9662?atlOrigin=eyJpIjoiNTk3OWZ... ) Re: IllegalArgumentException when composite ID has IDENTITY generated value ( https://hibernate.atlassian.net/browse/HHH-9662?atlOrigin=eyJpIjoiNTk3OWZ... ) I have found that this fails with sequences too, when the composite identifier is another entity. This works: @Id @Column(name = "registration_number" ) @GeneratedValue(strategy = GenerationType.SEQUENCE) private Long registrationNumber; @Id @Column(name = "publisher_id" ) private Integer publisherId; but, this does not: @Id @Column(name = "registration_number" ) @GeneratedValue(strategy = GenerationType.SEQUENCE) private Long registrationNumber; @Id @JoinColumn(name = "publisher_id" ) @ManyToOne private Publisher publisherId; The exception thrown is: javax.persistence.PersistenceException: org.hibernate.HibernateException: No part of a composite identifier may be null at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:154) at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181) at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188) at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:716) at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:696) at x.Testclass.x(Testclass.java:56) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209) Caused by: org.hibernate.HibernateException: No part of a composite identifier may be null at org.hibernate.tuple.entity.AbstractEntityTuplizer$IncrediblySillyJpaMapsIdMappedIdentifierValueMarshaller.getIdentifier(AbstractEntityTuplizer.java:365) at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:219) at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:5119) at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4819) at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:294) at org.hibernate.event.internal.EntityState.getEntityState(EntityState.java:59) at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:95) at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55) at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:710) ... 25 more ( https://hibernate.atlassian.net/browse/HHH-9662#add-comment?atlOrigin=eyJ... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-9662#add-comment?atlOrigin=eyJ... ) 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#100125- sha1:a1a1592 )