Oliver Drotbohm ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=5ed8acf... ) *created* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiOGU5NDAyZDg4... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-15552?atlOrigin=eyJpIjoiOGU5ND... ) HHH-15552 ( https://hibernate.atlassian.net/browse/HHH-15552?atlOrigin=eyJpIjoiOGU5ND... ) Embeddable type cannot be cast to org.hibernate.usertype.CompositeUserType if referred to from a mapped superclass with generic parameter ( https://hibernate.atlassian.net/browse/HHH-15552?atlOrigin=eyJpIjoiOGU5ND... ) Issue Type: Bug Affects Versions: 6.1.3 Assignee: Unassigned Components: hibernate-entitymanager Created: 26/Sep/2022 06:05 AM Priority: Major Reporter: Oliver Drotbohm ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=5ed8acf... ) Trying to upgrade a project from Hibernate 5 to 6 I run into the following issue: class ….MyEmbeddable cannot be cast to class org.hibernate.usertype.CompositeUserType (….MyEmbeddable and org.hibernate.usertype.CompositeUserType are in unnamed module of loader 'app') at org.hibernate.type.ComponentType.<init>(ComponentType.java:113) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.mapping.Component.getType(Component.java:255) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.internal.AttributeFactory.determineAttributeMetadata(AttributeFactory.java:375) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.internal.AttributeFactory.buildAttribute(AttributeFactory.java:111) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.internal.AttributeFactory.buildAttribute(AttributeFactory.java:96) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.internal.MetadataContext.wrapUp(MetadataContext.java:331) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.model.domain.internal.JpaMetamodelImpl.processJpa(JpaMetamodelImpl.java:504) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.model.domain.internal.MappingMetamodelImpl.finishInitialization(MappingMetamodelImpl.java:244) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.metamodel.internal.RuntimeMetamodelsImpl.finishInitialization(RuntimeMetamodelsImpl.java:60) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:308) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:415) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1425) ~[hibernate-core-6.1.3.Final.jar:6.1.3.Final] The rough arrangement looks like this (pseudocode): @Embeddable class MyEmbeddable { } @MappedSuperclass class SuperType<T> { MyEmbeddable embeddable; } @Entity class ConcreteType<T> extends SuperType<T> { } org.hibernate.cfg.ClassPropertyHolder.addPropertyToMappedSuperclass(Property, XClass) runs into a special branch of the code if the mapped superclass has generic parameters. In that case, it ultimately ends up calling setTypeName(…) with the type name of the embeddable as parameter. ComponentType later inspects that type name and tries to resolve it in its constructor, unconditionally casting it to CompositeUserType. Find a reproducer here ( https://github.com/odrotbohm/hibernate-bugs/tree/main/generic-mapped-supe... ). $ git clone https://github.com/odrotbohm/hibernate-bugs $ cd hibernate-bugs/generic-mapped-superclass $ mvn clean test // works, Hibernate 5 $ mvn clean test -Phibernate-6 // fails as described above, Hibernate 6.1.3 Hope that helps further diagnosing the problem. ( https://hibernate.atlassian.net/browse/HHH-15552#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-15552#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#100207- sha1:1c92a42 )