Loukas Mouzos ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiZmUzZTNjZDcy... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-16166?atlOrigin=eyJpIjoiZmUzZT... ) HHH-16166 ( https://hibernate.atlassian.net/browse/HHH-16166?atlOrigin=eyJpIjoiZmUzZT... ) ClassCastException, mixing mapping types for same field name on different entities ( https://hibernate.atlassian.net/browse/HHH-16166?atlOrigin=eyJpIjoiZmUzZT... ) Change By: Loukas Mouzos ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) We have a setup of a base entity which is inherited by many other entities. We use the inheritance type {{InheritanceType.JOINED}}. In case the child entities have same field name but with a different type, a {{java.lang.ClassCastException}} is thrown during the initialization of the session factory (during post init callbacks): {noformat}Caused by: java.lang.IllegalStateException: PostInitCallback queue could not be processed... - PostInitCallbackEntry - Entity(model.BaseObj) `sqmMultiTableInsertStrategy` interpretation at org.hibernate.metamodel.mapping.internal.MappingModelCreationProcess.executePostInitCallbacks(MappingModelCreationProcess.java:146) at org.hibernate.metamodel.mapping.internal.MappingModelCreationProcess.execute(MappingModelCreationProcess.java:90) at org.hibernate.metamodel.mapping.internal.MappingModelCreationProcess.process(MappingModelCreationProcess.java:39) at org.hibernate.metamodel.model.domain.internal.MappingMetamodelImpl.finishInitialization(MappingMetamodelImpl.java:229) at org.hibernate.metamodel.internal.RuntimeMetamodelsImpl.finishInitialization(RuntimeMetamodelsImpl.java:60) at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:311) at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:415) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:754) at org.hibernate.testing.junit4.BaseCoreFunctionalTestCase.buildSessionFactory(BaseCoreFunctionalTestCase.java:129) at org.hibernate.testing.junit4.BaseCoreFunctionalTestCase.buildSessionFactory(BaseCoreFunctionalTestCase.java:114) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at org.hibernate.testing.junit4.TestClassMetadata.performCallbackInvocation(TestClassMetadata.java:203) ... 14 more Suppressed: java.lang.ClassCastException: class org.hibernate.mapping.Set cannot be cast to class org.hibernate.mapping.SimpleValue (org.hibernate.mapping.Set and org.hibernate.mapping.SimpleValue are in unnamed module of loader 'app') at org.hibernate.dialect.temptable.TemporaryTable.lambda$createEntityTable$4(TemporaryTable.java:340) at java.base/java.util.LinkedHashMap$LinkedValues.forEach(LinkedHashMap.java:647) at org.hibernate.persister.entity.AbstractEntityPersister.visitDeclaredAttributeMappings(AbstractEntityPersister.java:6135) at org.hibernate.persister.entity.AbstractEntityPersister.visitSubTypeAttributeMappings(AbstractEntityPersister.java:6855) at org.hibernate.dialect.temptable.TemporaryTable.lambda$createEntityTable$5(TemporaryTable.java:336) at org.hibernate.dialect.temptable.TemporaryTable.<init>(TemporaryTable.java:145) at org.hibernate.dialect.temptable.TemporaryTable.createEntityTable(TemporaryTable.java:250) at org.hibernate.dialect.H2Dialect.getFallbackSqmInsertStrategy(H2Dialect.java:643) at org.hibernate.query.sqm.mutation.internal.SqmMutationStrategyHelper.resolveInsertStrategy(SqmMutationStrategyHelper.java:87) at org.hibernate.persister.entity.AbstractEntityPersister.interpretSqmMultiTableInsertStrategy(AbstractEntityPersister.java:5972) at org.hibernate.persister.entity.AbstractEntityPersister.lambda$prepareMappingModel$12(AbstractEntityPersister.java:5825) at org.hibernate.metamodel.mapping.internal.MappingModelCreationProcess$PostInitCallbackEntry.process(MappingModelCreationProcess.java:210) at org.hibernate.metamodel.mapping.internal.MappingModelCreationProcess.executePostInitCallbacks(MappingModelCreationProcess.java:108) {noformat} This is working with older Hibernate version {{5.6.14}} . h3. Simple use case BaseObj.java {code:java}@Entity @Inheritance(strategy = InheritanceType.JOINED) public class BaseObj { @Id long id; }{code} Author.java {code:java}@Entity public class Author extends BaseObj { String comments; }{code} Post.java {code:java}@Entity public class Post extends BaseObj { @OneToMany(mappedBy = "post") Set<Comment> comments; }{code} Comment.java {code:java}@Entitypublic class Comment extends BaseObj { @ManyToOne   Post post; }{code} I have added a test case with the entities here [https://github.com/lmouzos/hibernate-test-case-templates|https://github.c...] ( https://hibernate.atlassian.net/browse/HHH-16166#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16166#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#100215- sha1:a0f3b6a )