Moritz Becker ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *created* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiZjUwZTM2YTBm... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-16993?atlOrigin=eyJpIjoiZjUwZT... ) HHH-16993 ( https://hibernate.atlassian.net/browse/HHH-16993?atlOrigin=eyJpIjoiZjUwZT... ) Collection converter on Collection typed attribute not working ( https://hibernate.atlassian.net/browse/HHH-16993?atlOrigin=eyJpIjoiZjUwZT... ) Issue Type: Bug Affects Versions: 6.2.7 Assignee: Unassigned Attachments: collection-converter-issue-reproducer.zip Components: hibernate-core Created: 25/Jul/2023 22:52 PM Priority: Major Reporter: Moritz Becker ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) When annotation a java.util.Collection typed entity attribute with a Hibernate collection converter the entity loading / attribute conversion fails with a ClassCastException. Changing the attribute declaration to a List or a Set fixes the issue. This used to work in Hibernate 5.6. @Entity public class Person { @Id private Long id; @Column @Convert(converter = DogListConverter.class) // Change declaration to List<Dog> to make the test pass private Collection<Dog> dogs = new ArrayList<>(0); } collection-converter-issue-reproducer.zip ( https://hibernate.atlassian.net/rest/api/3/attachment/content/50529 ) ( https://hibernate.atlassian.net/browse/HHH-16993#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16993#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#100233- sha1:62cfdef )